An opposition fighter holding a rocket propelled grenade (RPG) as his fellow comrades take cover from an attack by regime forces in Khanasser on Monday

Drums of war: As-it-happens

Drums of war: As-it-happens

16:34 –And with that we'll bring the live blog to a close. We will be back up and running early tomorrow morning and with you all the way through to 10pm for the vote. It's going to a long, long day. See you then.

16:22 – More from Alex Stevenson, this time with the anti-intervention camp:

If a Commons majority for action is secured, the wording of the government motion will have to be crafted very carefully. Many of the MPs I've spoken to who oppose any kind of action sound as if they have already made up their minds.

John Baron, a member of the foreign affairs committee, is one of them. He wants to see a renewed diplomatic effort in the UN and is clearly uncomfortable with the idea of armed intervention.

"This is a vicious civil war, with atrocities committed by both sides," he tells me. He is sceptical about the proof the government claims it possesses that Bashar al-Assad is responsible. Michael McCann, who says he is "right on the line on this one", says he'd wager it was Assad but thinks it's important the evidence backing that up is produced. "I don't see how events in Syria, however terrible, affect people in Britain," he says. The message from his constituents is 'what has this got to do with us?'

The reason for that, he says, lies in Britain's most recent foreign misadventures. "Iraq and Afghanistan are indelibly tattooed in the minds of the British people. Even the sight of the children on the TV screens isn't moving them to [call for] action. There is tons of compassion, but no stomach for action."

Roger Godsiff voted with his party leader in 2002 when the Commons approved a declaration of war against Saddam Hussein's Iraq. "We were conned," he says. The memory still rankles and he is not likely to be "conned" again. "I've met Assad," he says. "The guy's not an idiot. He runs an old-fashioned communist regime, they've all got their noses in the trough. They're not going to give up easily and they have the backing of Russia."

MPs studying the arguments carefully will find themselves troubled by the risks inherent with both action and inaction – but more seem ready to see the dangers of making an intervention than otherwise. Baron says Syria is a proxy war on many levels: between Russia and the west, between Sunni and Shia, between Iran and Saudi Arabia. That is, by itself, put forward as a reason for caution. Godsiff paints a picture of international catastrophe stemming from a western intervention: terrorists in the rebel numbers having their interests promoted by the west, Israel being drawn into a regional conflict, Russia deciding to "turn the taps off" on its energy supplies to Europe. His voice reaches an uncomfortably high pitch before he finally stops talking.

16:11 –I thought that was a very impressive statement from Hague, who excells at these big occassions. One caveat – a little later he stressed that the rebel forces do not have the capacity to launch a chemical attack, contrary to the UN team mentioned earlier. Certainly, you would not have got the impression of uncertainty listening to him. However, his argument that this was the first chemical attack of the century and needed to be stamped on to prevent bigger ones in the future will be repeated tomorrow. We also got a very strong statement that the UK is not prepared to wait for the UN weapon inspection team. That runs counter to Ban Ki-moon, who just moments ago said: "Let them conclude their work in four days. Then I think we will have to report to the security council for any actions which they may deem it necessary to take."

16:07 – William Hague is giving a statement.

It's time the UN security council shouldered its responsibilities on Syria which for the last two-and-a-half years it has failed to do. [The UN resolution] demands the Assad regime ceases to use such weapons. I expect there will be further discussion in New York over the coming days. By far the best thing would be if the UN could be united, unlikely as that seems in the face of vetoes from Russia and China that we've had in the past, but we have to try. If there's no agreement we still have a responsibility on chemical weapons. This is the first use of chemical weapons in the 21st Century. We have to confront something that is a crime against humanity, if we don't do so we will have to confront even bigger war crimes in the future.

16:00 – There are reports Assad is already moving his troops into cultural squares, historic sites, and residential neighborhoods. 

15:57 –Stand by for a long update from Alex Stevenson, who has been talking to MPs about how they plan to vote all day.

Emotion and cold logic are sitting side-by-side in the pro-intervention camp, where MPs likely to support the government in tomorrow's debate are united by a simple impulse: the need to respond to an appalling chemical weapons attack.

Richard Ottaway, the chair of the Commons' foreign affairs committee, has left emotion by the door. He believes western credibility is on the line after Barack Obama made clear the use of chemical weapons was a "red line" which would change the "equation". "Doing nothing is not an option," he tells me. "If we do nothing, we are effectively endorsing the actions of a mass murderer." He thinks a missile attack would be the best option, rather than sending boots in on the ground. And while Ottaway accepts emotion doesn't come into the equation in his own thinking, he accepts the arguments are powerful both ways.

Penny Mordaunt, the Tory backbencher, is horrified. The use of chemical weapons by Assad has convinced her an intervention is needed, but she'll only support it if its focus is firmly on getting rid of them. Mordaunt thinks the UK's previous reluctance to intervene, instead focusing on diplomatic progress while containing the situation, has been the right one. Now chemical weapons have been used, that "changes the dynamic completely". When I put it to her that a chemical is not necessarily worse than a bullet', she insists it very much is. "Chemical weapons are, as well as being particularly nasty, have lasting effects for generations," she explains. Many of the thousands of people who have survived the attack will have children with birth defects as a result of the attack. "Whatever the conflict, there are certain rules of engagement that people abide by."

Labour MP Mike Gapes, Ottaway's predecessor in charge of the foreign affairs committee, does not trust anyone in Syria or the wider region to abide by them. He is passionately in favour of intervention – and doesn't think a missile strike by itself would be sufficient to get the job done. "You can't destroy chemical weapons stocks simply by using cruise missiles," he says. Instead Arab countries may have to send people in. Perhaps the Russians could be persuaded to turn their backs on Bashar al-Assad. "Frankly, the international community has got to act… I've been getting very angry."

The Syria question is one which is cutting across party lines and leaving all those grappling with it feeling deeply uncomfortable. Those favouring intervention are being lambasted by waves of cynicism online, and they don't like it one little bit. "There are no easy options here," Gapes says. "All are bad." That doesn't mean he won't support government action in favour of intervention to the hilt. The expectation is that MPs supporting the motion will end up winning the vote, but no-one is ready to say that with any confidence just yet.

15:52 – Angry denounciations of Assad from Recep Tayyip Erdogan, prime minister of Turkey, which has more right to speak on issues around Syria than most given it is hosting 500,000 Syrian refugees. "So do we stand by the murderer al-Assad and his supporters?" he asked a rally of supporters. "We believe that giving consent to the killing of one person means giving consent to the killing of all of humanity. Consequently, we couldn’t allow that." He's much more liberal now he's not tear gassing demonstrators.

15:48 – The Guardian has a useful interactive map of the international response to Syria, although I must say my reaction to it was the same as every world map: 'Wow. Russia is MASSIVE'.

15:42 In another worrying sign, Israel has caled up its reservists. The small-scale mobilisation is being accompanied by the strengthening of its missile defences. "Following a security assessment held today, there is no reason for a change to normal routines," prime minister Benjamin Netanyahu said in a statement. "We are, in parallel, preparing for any scenario."

15:38 – Tom Harris is always one of Labour's more sober and thoughtful MPs, but he's outdone himself today with a smart, worthwhile piece admitting he really doesn't know how to vote tomorrow. Particularly worthy of mention is his second-to-last point on whipped votes for issues of war and peace. If we give free votes on issues like gay marriage, surely substantive keep-you-up-at-night votes like tomorrow's should also be free.

15:08 – Labour's whole strategy, of course, is designed to differentiate Miliband's leadership from Blair's and get out from underneath the shadow of Iraq. Labour's had three positions on this (consistent, but not exactly clear) over the last 24 hours. You can feel the party agonising. Ultimately, it is all theatre. Russia and CHina are never going to back anything which allows for intervention, no matter what the weapon inspectors show them. And anyway, the inspectors' report isn't tasked with establishing who did it, although that may become clearer given the details of the substance and the delivery system. That being said, theatre, at an international level, should not underestimated. It is politically relevant.

15:04 –Labour has fleshed out the details of its policy vis-a-vis the UN. It;s now inly prepared to support he government if the UN security council has the chance to look at the UN weapons inspectors' report into the chemical attack. However, the inspectors are expected to need another five days before they can file the report. So either Labour will abstain tomorrow or attach an amendment to the motion. 

15:00 –Here's a Downing Street spokesperson on the national security council meeting:

The national security council met this afternoon to consider the government’s response to the appalling chemical weapons attack near Damascus last week. The NSC agreed unanimously on a recommendation that the Cabinet will consider tomorrow. Ministers agreed that the Assad regime was responsible for this attack and that the world shouldn’t stand idly by; and that any response should be legal, proportionate and specifically to protect civilians by deterring further chemical weapons use. There was unanimous backing for the approach we are pursuing at the United Nations and the Chapter VII resolution put forward to fellow P5 members today.

14:44 – Peter Hain, former Welsh secretary, has come out strongly against intervention. Here are his quotes from the Guardian:

This is a highly complex civil war in a region where the wrong action could light a powder keg, with not just consequences for refugees that we have already seen but retaliatory action against other countries … [Bashar al-Assad, the Syrian president] has formidable weaponry supplied by the Russians and the Iranians. The prime minister is asking the nation to back him on a dangerous strike when nobody knows what the consequences will be. I think that's very, very dangerous politics."

14:16 – As if to focus the mind, reports have emerged that a series of co-ordinated bombings in Baghdad have killed more than 50 people and wounded dozens. The bombs targeted mostly Shia neighbourhoods.

14:12 –The secuirity meeting is now over. Among the people leaving were head of Britain's armed forces, General Sir Nick Houghton and MI6 chief Sir John Sawers as well as attorney general Dominic Grieve.

14:10 – The Scottish government also opposes military intervention in Syria. You can see Alex Salmond's full statement here, but here are the key bits:

Any resort to military action should always be approached carefully, on an evidential base, and within a clear legal framework – and only after full consideration of the aims, objectives and consequences. At this stage, we consider that these criteria have not been met and therefore that the case for military action in Syria – or the UK’s participation in it – has not yet been made.

13:21 – Here's probably the most resolute anti-intervention piece in the press today, by the Guardian's Seumas Milne.

13:16 – There's a protest outside Downing Street by the Stop the War Coalition tonight from 5pm. Their statement is here but key bits are below:

It seems that the Western governments have already made up their minds about this attack before it has even been reported on by UN weapons inspectors. They are demanding that ‘something must be done’ even though their record of ‘doing something’ has been nothing short of catastrophic. There have been numerous western interventions in the Middle East and South Asia over the past 12 years. While the attacks on Afghanistan, Iraq and Libya were all argued for on humanitarian grounds, they have all increased the levels of killing and misery for the ordinary people of those countries. They were in reality all about regime change. This is also what Syria is about. The truth is that this latest plan is about intervening to reshape the Middle East in the strategic interests of the West.

13:05 – Caroline Lucas, parliament's only Green party MP, has demanded that parliamentarians see legal advice on a Syrian intervention before voting tomorrow. This is from her blog:

Following the reports of the chemical weapons atrocity in Damascus, parliament has rightly been recalled.  I have long argued that parliament should be guaranteed a free (un-whipped) vote before any involvement in conflict. It is vital, however, that MPs' deliberations are informed by all relevant information, and based on sound legal grounding.  I have therefore written to the prime minister today, calling on him to publish the legal opinion that he will have sought on military action, and to place this before MPs in advance of the vote. All MPs have to decide on Thursday how best to respond based on the balance of risk.  Our guiding principle has to be preservation of life and humanitarian concern.  But I have yet to see any evidence that an attack is likely to deter rather than escalate conflict in the region."

12:44 – I apologise for the break. There were (predictable) technology problems and then (equally predictable) I wrote a blog on the anti-war left's response to the crisis. You can read that here.

10:56 – Here's an alternate view from Patricia Lewis, research director on international security at Chatham House. Click here for the full blog.

Each piece of evidence forms part of the puzzle. The first is the chemical used and its concentration. This helps narrow down who had access to it; if it is sarin for example (and the symptoms suggest it was) then the source of the weapon is likely to be government stocks. This is particularly true if the chemical weapon contains other chemicals such as stabilizers and dispersal agents. It could be from another organophosorus compound sourced from the agricultural sector, but it is unlikely that normal agri-products could have had such a devastating impact in such a short space of time. The inspectors need to do due diligence and investigate in order to rule out or still entertain the full range of possibilities.

10:49 – Here's something worrying to complicate matters further. It's just been brought to my attention on Twitter that chemical weapon attacks could well have been conducted by rebel forces. US and UK officials have been keen to argue that there's no way the rebels could have executed the attacks, but a senior UN diplomat does not necssarily feel the same way.

10:45 – Some pertinent points here from Michael Williams, acting head of the Asia programme at Chatham House, particularly on the role of Iran and Hezbollah in any military intervention. For the full blog click here.

In looking at an increasingly probable, perhaps inevitable, US led strike on Syria it is useful to recall similar military actions in Kosovo in 1999 and, more recently, in Libya in 2011. In both cases neither Serbia nor Libya had friends whose support they could rely on. This is not the case with Syria.

Unlike Serbia or Libya, Syria is firmly embedded in an alliance with Iran and Hezbollah, almost certainly the most heavily armed non-state actor in the world. While it is improbable that Iran would engage in overt military action in retaliation for the expected US led raids, it is highly probable that Hezbollah would deepen its assistance to the Syrian regime whose downfall it could not tolerate. It could do so in several ways by threatening and even attacking UNIFIL, the ten thousand strong peacekeeping missions in southern Lebanon, which has a high number of troops from NATO countries in its ranks including France, likely to join any military action against Syria, as well as Italy and Spain. It might even seek to break the cessation of hostilities with Israel which has lasted since the 2006 war.

10:35 – A bit more on the opinion polls. Here, as in the parliamentary debate, everything is overshadowed by Iraq. It looks very bad for Cameron and co. They have a mountain to climb before the public are ready to back military intervention. The public opposes a missile attack by two-to-one. Only one person in four said the chemical attacks made them more favourable to military action. But as YouGov boss Peter Kellner writes, a quarter of voters are undecided and these people – along with a few antis – tend to swing into line to 'support our troops' once military action starts. Read more about the poll here.

10:28 – The latest from Alex Stevenson, who has been told that Cameron and Hague have started working on the Commons motion before the security council meeting 

Such is the rushed nature of this vote that, even the day beforehand, it's very difficult to tell how it's all going to pan out. The main reason for this being, of course, that the government's policy is not yet set in stone. The national security council is meeting today but a coalition source has told me a draft of the government motion to be put to a vote tomorrow is already being debated between David Cameron and William Hague. Hashing out the wording is a process which will be informed by the NSC, but the bare bones of the intervention – widely expected to be a missile strike – looks like it has already been settled on.

Nevertheless, the timing of its publication will be significant. If it's released tomorrow morning rather than this evening that will be a clear signal of  internal government agonising. MPs I've spoken to are already clamouring to read the text. Until it's released, even broadbrush speculation about the result will be premature.

10:23 -'It;s likely that that UN resolution is the result of Labour's overnight conversion to the need for a "UN moment". Miliband was rather more supportive last night, but this morning a Labour spokesperson said:

We have made it clear that we want to see a clear legal basis for any action. As part of the legal justification, Labour is seeking the direct involvement of the United Nations through the evidence of the weapons inspectors and consideration by the security council.

It's clearly designed to but the concerns of people like Diane Abbott to bed, but it seems a futile gesture. The resolution is unlikely to pass.

10:19 – Britain has drafted a resolution for the UN security council to condemn the use of chemical weapons by Assad and authorise "necessary measures to protect civilians". Cameron has taken to making significant announcements on matters of national security and international relations via the medium of Twitter, so I'll embed the relevant messages below:

10:10 – This Telegraph blog from Iain Martin is worth reading on the reprecussions for Cameron if he loses tomorrow's vote. As we've seen today, many people's default position is opposition, so it is not unthinkable. In Martin's words a lost vote would mean that he's "toast". He makes several good points, including:

  • Cameron is a reluctant interventionist
  • A narrowly drawn motion will limit room for operational manoivres but a broader one will be treated as a 'blank cheque'
  • It's very hard to predict how the Lib Dem or Tory backbenchers will vote

09:54 – More on the military strategy, as far as we can establish it:

The national security meeting Cameron will be attending today will also include defence secretary Phillip Hammond, home secretary Theresa May and deputy prime minister Nick Clegg, as well as military and intelligence chiefs.

We know leaders plan for the strikes to be proportionate and focused on limiting future use of chemical weapons rather than regime change. That still leaves a lot of room, however. It could specify a strike against chemical weapons themselves or be a broader definition in which punishing Assad for using them originally is still said to have limited their future use.

A nearby British Trafalgar class submarine could be used as a launch platform for a cruise missile strike. HMS Tireless is understood be in Gibraltar and could make the trip relatively quickly.

The Royal Navy's response force task group is already in the region for a pre-scheduled deployment. It includes helicopter carrier HMS Illustrious and frigates HMS Montrose and HMS Westminster. RAF Akrotiri airbase in Cyprus could also be employed in an intervention.

The US Navy is understood to be re-positioning several vessels, including four destroyers with cruise missile capacity and a submarine. If further firepower is needed, two US aircraft carriers could launch strikes from bases in Turkey and Cyprus.

The French would likely participate in the form of air power.

09:35 – And here's Nigel Farage, and by extention I suppose Ukip, opposing military intervention in Syria. He's surprisingly robust.

09:31 – And Reuters have taken these comments, which are somewhat daunting, from the Iranian supreme leader. He said US intervention in Syria would be "a disaster… the region is like a gun powder store and the future cannot be predicted". 

09:27 – Here's the full read-out from the PM's call with Obama, via a Downing Street spokesperson:

"The PM spoke to President Obama last night to further discuss the serious response to last week's chemical weapons attack in Syria. Ahead of today's NSC, it was an opportunity for the PM to hear the latest US thinking on the issue and to set out the options being considered by the government. Both leaders agreed that all the information available confirmed a chemical weapons attack had taken place, noting that even the Iranian President and Syrian regime had conceded this. And they both agreed they were in no doubt that the Assad regime was responsible. Regime forces were carrying out a military operation to regain that area from the opposition at the time; and there is no evidence that the opposition has the capability to deliver such a chemical weapons attack. The PM confirmed that the government had not yet taken a decision on the specific nature of our response, but that it would be legal and specific to the chemical weapons attack."

09:13 – On the question of legality, here is lobby journalist Adel Darwish speaking to Al-Jazeera. He's particularly well-versed in the legal arguments for military action without security council authorisation. 

09:09 – Abbott is not alone. There actually appears to be more discomfort on the Tory benches than on the Labour ones. This, by the way, will be a whipped vote (it always is on matters of war and peace) by all three party leaders.

On the Tory benches, John Baron said the vote may be "closer than it was over the Iraq war", Sarah Wollaston said she plans to vote against because of the risk it "could explode a proxy war into global conflict" and John Redwood said many of his colleagues "need persuading that there is any military intervention which the UK could make which would make it better".

Tim Farron, Liberal Democrat president, accepted the moral case for intervention but not necessarily the strategic case, saying it could "make a dreadful situation worse".

In a sign of how torn many MPs are, Labour deputy leader Harriet Harman appealed to her constituents on Twitter for them to help her make up her mind.

08:47 – Diane Abbott, shadow health minister, has just been on the Today programme discussing her concerns over the prospect of military intervention. She was repeastedly pressed on whether she would resign if she could not support her party's policy, but she refused to be drawn on that. Her two main objections seemed to be the lack of UN backing and a clearly-defined endgame. Here are as many of her quotes as I could get down:

The British public have seen this movie, they know how it ends. It's not clear any such bombing would be legal. The danger is we get dragged into a civil war in the Middle East. I would be in favour of a UN-led intervention but a unilateral US-led strike will not carry the international community with it. If you have to get everyone behind you – like Russia, like China, like Europe – it's more likely to be a well-thought-out intervention. People who have actually fought in a war are much more thoughtful about sending others into it. It's a really important vote. We need to have a vote on legality. There's a danger we're being stampeded into this. I'm waiting to see the motion. I can't tell you what I'll do until I can see the motion.

Elements of Abbott's comments, such as the section on Russia and China getting behind any action against Assad, eem slightly niave. But the central thrust of her objections – the comparison with Iraq on the lack of a UN-mandate and the concerns around exactly what intervention would achieve – are cited across the political spectrum, and by regional experts and academics. For comparison, it's worth reading the piece written for us by Stefan Wolff, professor of International Security at the University of Birmingham.

08:34 – Good morning. We'll be here throughout the day covering the build-up to military intervention in Syria, which has now become a matter of 'when', not 'if'. That does not necessarily apply to Britain however, with MPs headed to the Commons tomorrow to discuss the plans. Prominent figures on all sides of the House are expressing deep reservations. It is quite possible they will reject the prospect of military action, leaving David Cameron in a serious quandry. In other developments, polling shows the British public are also deeply uncomfortable with British involvement and Cameron will attend a national security meeting following a phone call with Barack Obama. I'll be manning the blog until about lunchtime, when I run off to do an interview and Alex Stevenson takes over. Developments are now coming thick and fast and we'll be bringing all of them to you on the blog as they break.