Ten hours of debate ended with an overwhelming vote Wednesday evening approving military strikes against suspected "Islamic State" militants inside Syria.

Prime Minister David Cameron asserting that bombing the "medieval monsters" in their heartland would make Britain safer.

Within hours of the measure passing, the UK's Ministry of Defence confirmed that the first airstrikes had been carried out using RAF Tornado jets.

Hours-long debate

Cameron won the backing of lawmakers after an often emotional all-day debate in which opponents argued his military plan was based on wishful thinking that overlooked the messy reality of the Syrian civil war.

"The question is this," Cameron said in his appeal. "Do we work with our allies to degrade and destroy this threat and do we go after these terrorists in their heartlands, from where they are plotting to kill British people? Or do we sit back and wait for them to attack us?"

Britain is already bombing suspected IS targets in Iraq, and in September launched a drone strike that killed two suspected British IS militants in Syria.

Vociferous opposition from minority

Public opinion in Britain is divided over launching the strikes, with a YouGov opinion poll showing voter support for action in Syria had fallen to the lowest level since September 2014, with 48 percent of respondents supporting strikes and 31 percent against.

Opposition Labor Party leader Jeremy Corbyn voiced strong opposition despite dozens from his own party backing the government's mandate for airstrikes.

"To oppose another reckless and half-baked intervention isn't pacifism. It's hard-headed common sense," he said

Earlier this week the German cabinet also resolved to join the air campaign against IS, though in a support role. A full vote by the Bundestag is expected later this week.

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jar/gsw (Reuters, AP)