Former Deputy Prime Minister Nick Clegg warns against exaggerating the pros and cons of military action as the Liberal Democrats back the Conservatives.
The Sheffield Hallam MP said that when France asked for help and the recent United Nations backing had strengthened the case for the aerial bombardment of Islamic State (IS).
However since the country is already at war with IS in Iraq, the decision to extend the geographical range of bombing into Syria should not be over-stated
He said: "I'm minded to support the extension. Not really because of the military argument because just as much as opponents exaggerate the risks, we are already in a war with Isil. We are already chucking bombs at them and I think people slightly exaggerate what a step it is when they criticise it."
"Equally I think people who overstate what will be gained militarily are also overstating their case. The idea that extra British bombs will militarily change the dynamic completely is stretching credibility.
"I just don't think anyone should overstate the case for or against. We are already at war, we are already dropping bombs from 30,000 feet, we are already conducting surveillance missions over Syria, they are already attacking us, they've already murdered Brits on the beaches of Tunisia. It's already highly likely there's going to be an attack on British soil at some point."
He said France's request for help from the RAF had been a key moment in helping him make up his mind.
"[France] are an incredibly important ally of ours. If that had happened in London and we asked the French, I think we would want the French to try and help us out as one of our closest, nearest neighbours," he said.
UN backing, Iran and Russia's participation in talks have also shifted the political arena since the Coalition asked MPs to vote on bombing Iraq when he was Deputy Prime Minister, he said.
"I think two things have changed in addition to the attacks in Paris. One is that there has been a significant vote in the United Nations, which was very unambiguous in calling on all member Governments to do everything they could to degrade Isil and secondly Russia and Iran are now much more fully involved in the discussions about how to plot a way forward in Syria which was always lacking in the past.
"I won't overstate it more than that. There is at least a window of opportunity now for a more durable and diplomatic solution.
"My judgement is there are huge risks, it might not work, but on balance it is right for us to have a voice at that top table."
"Inaction doesn't help you very much but military action on its own isn't the solution either," said Mr Clegg who said the lesson from the Iraq war must be that there is also a well thought out political strategy.