In the last few days Westminster's focus has naturally been on how the UK government responds to the attacks in Paris. But this most stark demonstration of the threat to national security is starting to cause quite serious problems for the - not so new any more - Labour leader Jeremy Corbyn.
Many Labour MPs were shocked after he told me he would not be happy with the police or security forces shooting to kill on our streets, casting doubt over the legality of the strike on Jihadi John, and appearing to suggest that his MPs would not be allowed to vote with their conscience on any potential military action in Syria.
For his supporters, those positions are quite consistent with his well-known objections to violence in any forms, and may be heartening, refreshing and principled.
In turn, those are some of the positions that Labour MPs in the more right-wing strands of the party find hardest to stomach.
But here's the rub. In recent days, and at last night's stormy meeting of Labour MPs, some of those in the centre of the party, members of the 'Make it Work' brigade, who took jobs in Jeremy Corbyn's team to help keep the party together, were among those expressing anger and disbelief, not just at the views that Mr Corbyn had articulated, but how during the meeting he did not, in some of their opinions, answer the questions that were put.
And in the words of one, he just tried to "waffle his way through". Frankly, I have rarely heard reactions like it.
One moderate shadow minister told me, as Corbyn struggled to answer questions on Syria and security: "I am trying to respect the mandate he has but I felt physically sick, I just couldn't stand it."
He went on to add: "He is not fit to be our leader or in any senior position in this country."
Another senior MP who again, has not been publicly criticising Corbyn but quietly trying to get on with parliamentary business, told me the Labour leader "fundamentally misunderstands" the nature of the security threat we face, and that he has shown in recent days that "none of his gut instincts chime with the public beyond his niche group".
Corbyn's team say only a minority of MPs protested "volubly" at last night's meeting.
Yet on BBC Radio 4's Today programme this morning, the well respected Shadow Foreign Secretary, Hilary Benn, who tried to intervene to calm the meeting down last night, struggled to agree with Corbyn's positions, and contradicted him completely on "shoot to kill".
Straining at existing tensions
Security, the most sensitive of subject areas, is straining at the tensions that were already there inside the Parliamentary Labour Party.
And there's a specific fight brewing that may bust those tensions wide open.
Mr Corbyn is planning to give a speech at a Stop the War fundraising dinner in December.
Their website says, "Jeremy's success is a victory for the anti-war movement to which he has contributed so much. Here is your chance to celebrate with the man himself".
It sounds like a minor event, but it is fast becoming a litmus test for some of his MPs.
Over the weekend, that organisation with whom Mr Corybn has been linked for many years, suggested that the Paris attacks were vengeance for Western actions in the Middle East.
Mr Corbyn disassociated himself from the specific remark yesterday, but for Labour MPs his connection with the event is a judgement call.
He was asked last night specifically not to go.
There was no clear answer, and this morning, his team are yet to respond.
Corbyn says he believes in peace, but if he is looking for a political fight in his own party, he's got one.