Nick Robinson: MPs will need persuading

The spectre of another war in another place in another decade hung over parliament today.

Iraq, David Cameron said, had poisoned the well of public opinion.

That is why the prime minister began his speech to the Commons today by listing what military intervention in Syria would not be.

It would, he claimed, not be about taking sides; not about regime change; not about an invasion.

Nevertheless, he faced doubts from MPs on all sides - doubts about the evidence, the legality, the consequences.

Ed Miliband demanded more time, more space and more evidence too. He faced accusations that he was merely playing politics.

MPs will get another vote after tonight before any military action. Even though that's what the Labour leader forced the government to promise, he and his party will vote against the government.

All the main party leaders are clearly struggling to find positions that their own supporters can back.

Tonight's vote is no longer going to be the final moment of decision about whether Britain will engage in conflict again.

What is clear is, if it does come to that, Parliament will need an awful lot of persuading.