Deputy Labour leader Tom Watson has written to David Cameron to say he believes there is a 'compelling case' for British airstrikes in Syria - but warned that more time is needed to reassure Labour MPs who are ready to back him.
In a letter, seen by the HuffPost UK, Mr Watson says that he believes there will be no 'broad consensus' that the Prime Minister seeks unless he answers key questions on ground troops and on the diplomatic process.
His missive came as Jeremy Corbyn sent his own letter to Mr Cameron requesting a two-day debate and a delay to any vote planned for this week.
His letter followed a tense, two-hour meeting of the Shadow Cabinet, which agreed a plan from Mr Watson and others to hold a free vote on Syria.
But with Mr Cameron keen to rely on Labour MPs to back him on the issue, the deputy Labour leader makes clear they may need more time - and answers - before they come on board.
Mr Watson's letter is as follows:
Dear Prime Minister
All Members of Parliament have approached the prospect of extended action in the ISIL held territory within Syria with a heavy heart.
You will be aware that the Shadow Cabinet met this afternoon to discuss your proposal to extend UK support for the military coalition against ISIL, from Iraq and into the territories it currently occupies in Syria.
I believe there is a compelling case for action based on the direct threat posed by ISIL to the United Kingdom and its citizens and to our allies. RAF air strikes have weakened ISIL in Iraq and based on the intelligence you presented to the House last Thursday, my understanding is that this action has not caused civilian casualties.
However, it is also clear that military action needs to be part of a bigger strategy, including ongoing political negotiations aimed at securing a lasting peace, and a comprehensive reconstruction plan in Syria. We also need a coordinated humanitarian effort to address the refugee crisis the war in Syria has created.
You are right to seek what you have described as a broad consensus in Parliament for the extension of military action into Syria. However, having spoken to many colleagues over the weekend, I don't believe you are yet in a position to reach such a consensus.
While many colleagues agree with the compelling moral and legal case for action, a large section of Labour MPs remain unconvinced about two areas in particular and would welcome more clarity on these issues.
Firstly, unlike in Iraq where there is a clarity of purpose and action by government led ground forces, it remains uncertain what the ground strategy in Syria would be and whether there is a coherent and capable ground force that could capitalise on the strategic advantage air strikes would give them.
This has been raised by colleagues in every political party. Your assertion that experts say there are 'approximately 70,000 Syrian opposition fighters on the ground who do not belong to extremist groups' has been widely challenged. Please could you explain, in detail, how this figure was compiled? The Chair of the Defence Select Committee said in the chamber that he was "extremely surprised" by this figure. His views carry great weight on both sides of the House. Are you able to explain to him, to me and others how the 70,000 figure can be used with confidence and provide more detail about where they are located?
Secondly, it is clear that military action needs to be part of a wider strategy, including ongoing political negotiations aimed at securing a lasting peace, and a comprehensive reconstruction plan in Syria. We also need a coordinated humanitarian effort to address the refugee crisis the war in Syria has created.
There are many MPs who understand that a transitional government in Syria can only come about if ISIL forces no longer hold territory. But they are yet to be convinced that there is a meaningful political process in place that can pull together the disparate groups who will need to sign up to it if there is to be a lasting peace.
I very much welcome the nascent Vienna Process. There needs to be a coordinated approach by all the military powers active- or in the UK’s case potentially active- in Syria. In particular we must ensure that those moderate opposition forces which have potential to take territory from ISIL are not weakened by military intervention.
However, I believe this can only come about once the Vienna Process begins to outline a broader strategy for Syria after military action has taken place. With this in mind, please can you outline a timeline for peace and the transition to arrangements for a lasting political settlement? And further to that, can you give an assessment and your view on the Saudi initiative to draw together opposition groups in Syria; how does the inclusion of conservative groups Arar Al-Sham and Jaish Al-Islam impact on the prospects for peace?
It is incumbent upon you as the Prime Minister to listen and engage with colleagues and to answer the legitimate questions I have raised on their behalf.
I do not believe you have given proper time to build consensus. As Jeremy Corbyn has made clear, parliament needs more time to make a considered decision on whether air strikes can take place. Only then can MPs from all parties confidently articulate that decision to their constituents and the British people.
Tom Watson MP
Deputy Leader of the Labour Party