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.
I have no doubt that every MP who sits on the green benches tomorrow will be united in their complete condemnation of the deplorable chemical attacks on civilians.
That's the easy part. But what do we do about it?
There is a genuinely difficult dilemma. President Obama cautioned in August 2012 that a major chemical-weapons attack by Assad's regime on Syrian civilians would cross a "red line". A year later, evidence that appears to point to just such an assault near Damascus, appalls us.
We should wait, of course, for the reports of the weapons inspectors. Our memories surely cannot be so short that the terrible consequences of pre-empting their investigations in Iraq have been forgotten.
Indeed, the many lessons that should be learned from the whole WMD fiasco ought to offer a new benchmark for MPs in holding Government to account - a process that would be made easier had the long-awaited Chilcot report been published, instead of apparently buried. It is nothing short of scandalous that the long awaited investigation into the Iraq War remains blocked and endlessly delayed.
But despite what may or may not be discovered by the Inspectors in the days to come, all the signs are that Obama and Cameron are not in any mood to pause. A military response looks almost inevitable - not one so serious as to topple the Assad regime and risk more power flowing to groups linked to Al-Qaeda, but one that aims to be a symbolic gesture: targeted but limited strikes, to send a signal that the use of chemical weapons against civilians will not be tolerated.
The question is whether this will really be the short, sharp, neat deterrent to further Chemical Weapons use, or whether - as many of us fear - it risks far more serious escalation.
Again, the wars in Afghanistan and Iraq teach us lessons we should not ignore. Early victories were hailed against the Taliban by Bush in December 2001 - yet the war in Afghanistan spanned a further decade. Triumphant howls heralded the fall of Saddam Hussein in May 2003, Bush pronounced 'Mission Accomplished' - yet in reality the bloodshed had only just begun.
It does no justice to the over 100,000 dead, the millions displaced and the victims of this apparent chemical weapons atrocity, to once again launch head first into intervention without closely considering whether it would be likely to make things better.
All Parliamentarians therefore 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. Where is the evidence that an attack is more likely to deter rather than escalate chemical weapon use?
Is ''quick, limited, clinical action' really possible? If it were, and it were clear that the result would be highly likely to be a stop to an escalation of chemical warfare, then it is arguably open to be considered.
But this preferred outcome is far from being guaranteed. To the contrary, there is at least as much evidence that it will act as a provocation to Assad and lead to escalation, and thus cause greater harm to civilians, particularly since Russia and Iran could simply increase their support for the current Damascus regime.
If the UK backs a US unilateral military raid, our chances of helping to get these other countries round a table for a diplomatic resolution will also be hugely undermined.
That being the case, and in the absence of clear legal advice being placed before members of parliament before any vote on Thursday, I do not feel able to support the governments over-played call for an ill advised and unplanned military response without even a whisper of overall aims or any future involvement or exit strategy.
For that reason, I will be tabling my own resolution for debate tomorrow, setting out that the case for military action against Syria has not been established.
Whatever happens next will affect many nations, so the UN must be at the centre of the discussion and decision making process, even if the widespread belief that Russia would veto any resolution proves correct.
Moreover, it is international law that has been flouted, and those responsible should be referred to the International Criminal Court for war crimes
The few non-signatories to the Chemical Weapons Convention include three states in the region, Egypt, Israel and Syria. The horror in Syria provides evidence that it is where states have not signed the Convention that the greatest dangers to civilians lie. This is another area where our diplomatic efforts should be intensified.
We must also stop arming states that at the same time we condemn as repressive, or who go on to arm repressive states themselves. The Government has issued over 3000 export licenses for military and intelligence equipment, worth a total of £12.3billion to countries which are on its own official list for human rights abuses.
A recent report by the Committee on Arms Exports Controls found there were 62 licenses for selling to Iran and 271 licenses for Russia. Both countries have been involved in large-scale supplies of weaponry to President Assad. This must stop.
And as a matter of urgency we should be increasing aid to Syria's neighbours to help them support the millions of families forced to seek refuge.
This blog was first published on Caroline Lucas' blog, and can be read here