British warplanes will once again be in the skies over Syria as the fallout continued from Parliament's decision to back air strikes.
Labour's leadership was forced to appeal for calm following a series of abusive messages aimed at MPs who backed military action, while police were investigating threats aimed at politicians who supported the bombing.
In an email to members urging unity following the vote on military action which split the party, Labour leader Jeremy Corbyn and his deputy Tom Watson insisted that "abuse and intimidation" would not be tolerated.
Mr Corbyn opposed air strikes while Mr Watson backed the action against Islamic State (IS) after the leader allowed his party a free vote on the issue after being unable to agree on a common position.
The two men wrote that the issue "has inevitably led to a big debate", adding: "Labour MPs voted by a clear majority against the air strikes in the end. But we agreed a free vote because of the sincerely-held differing views in the Parliamentary Labour Party."
In response to the hostility faced by MPs, they said: "Politics must be conducted in a better way - more civil and more respectful.
"We all support and defend the democratic right to protest and lobby. And all MPs must be open to hearing the views of their constituents and others on matters of public importance.
"But, as we have both said many times, abuse and intimidation have no place in politics. And the party as a whole will not accept such behaviour, from whatever quarter it comes."
Some MPs have said that messages attacking them came from social media addresses that appeared to be linked to Momentum, the organisation set up by Corbyn supporters in the wake of his successful leadership campaign earlier this year.
In a statement, the group said: "Momentum strongly disapproves of anyone who engages in abusive behaviour towards MPs or anyone else, and threatening or bullying, whether they are outside the Labour Party (as most are) or inside it.
"We specifically asked our supporters to emulate Jeremy Corbyn, and to keep their messages about the issues and to refrain from any personal attacks.
"Momentum is not a threat to MPs who voted for bombing. We have made clear that we will not campaign for the deselection of any MP and will not permit any local Momentum groups to do so. The selection of candidates is entirely a matter for local party members and rightly so."
But Labour MPs called for Mr Corbyn to publicly distance himself from Momentum.
"We need the office of the leader of the Labour Party to say Momentum is nothing to do with us, it's nothing to do with the Labour Party," former shadow cabinet minister Tristram Hunt told Channel 4 News.
He said there had been some "reprehensible comments from those involved in it but also intimidation of MPs and particularly intimidation of female Labour MPs".
Labour MP Neil Coyle, who complained to police about an alleged death threat he received on Twitter, told Sky News: "I don't blame Jeremy Corbyn, Jeremy Corbyn has made it absolutely clear he wants a different kind of politics, he wants more respect brought into the debate and he wants to genuinely consult and engage.
"Unfortunately, some of the people who pretend they act in his name and some of those who have surrounded him are doing things that he finds fundamentally unacceptable and they should respect his views as well as those of ordinary people in Britain who just don't think that this kind of behaviour is acceptable."
The Bermondsey and Old Southwark MP added that Mr Corbyn should "distance himself" from Momentum "very strongly".
"I have already asked him for a statement to protect Labour councillors and local Labour parties from some of the people who pretend they represent Corbyn," he said.
"Jeremy Corbyn's elected representatives are coming under pressure from people who think they are operating in the leader's name and only the leader and his team can take action to distance themselves from people who are not Labour representatives.
"I think, because of their behaviour, Labour members who are part of Momentum should resign from Momentum and just stay within the Labour Party."
Meanwhile, David Cameron came under fresh pressure over his claims that 70,000 fighters in Syria would be able to take on IS.
The Times quoted a senior Whitehall source warning that the figure could become the equivalent of Tony Blair's "dodgy dossier" claims ahead of the Iraq War.
"There were Ministry of Defence officials who maybe felt scarred after the previous dossier," the source said. "They looked at the latest text and said that (the 70,000 figure) could become the '45 minutes' moment of this document."
But a senior Ministry of Defence source told the Press Association: "As far as I'm aware we were fine with it (the 70,000 figure)."
Downing Street also insisted that no concerns had been raised by the MoD before the Prime Minister revealed the 70,000 figure in the Commons.
A Number 10 spokeswoman said: "The 70,000 figure was produced by the Joint Intelligence Committee, which includes in its membership officials from the Ministry of Defence.
"The Ministry of Defence did not raise concerns with No 10 on whether this figure should be included in the PM's response to the Foreign Affairs Committee."