UK Parliament votes to authorize airstrikes against ISIS in Iraq
The 524-43 vote came after Prime Minister David Cameron told Parliament that the country had a "duty to take part" in international efforts to combat the extremist group.
The terror group is an organization of "staggering" brutality, he said, which has already killed one British hostage and threatens the lives of two more.
"This is not a threat on the far side of the world," he said, but one which menaces European nations directly.
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In addition to an ISIS-inspired attack on a Jewish museum in Brussels earlier in the year, Europe's security agencies have disrupted six other ISIS-linked plots, he said.
Parliament was recalled by Cameron for the vote on military action in Iraq, which was approved after lengthy debate in the House of Commons and House of Lords. Any proposal to expand the strikes to Syria would require additional action by Parliament, according to the motion.
Cameron said Britain should join international allies in combating ISIS, a campaign that he warned would take years, not months. "The hallmarks will be patience and persistence, not shock and awe," he said.
The government insists such action is legal because Iraq's government has requested international help to tackle the Sunni extremist group, which has overrun vast swathes of Iraq and Syria and massacred religious minorities and Shia Muslims.
Cameron made that point again Friday, saying there was "no question" of the legality of action given the request by Iraq's leaders and the broad international backing for the campaign against ISIS.
Some MPs may be reluctant to back a bombing campaign in Iraq because of doubts over its effectiveness or unhappiness over past UK military intervention in Iraq.
But action has been backed by the governing coalition of the Conservatives and Liberal Democrats, as well as the opposition Labour Party.
Labour leader Ed Miliband told lawmakers the United Kingdom "cannot simply stand by" against the threat of ISIS.
Now that it's been approved, military action could start within hours. UK forces have already been taking part in surveillance missions over Iraq, as well as aiding Kurdish forces with equipment.
Cameron acknowledged that the memory of going to war in Iraq in 2003, when Labour's Tony Blair was Prime Minister, "hangs heavy" over the House of Commons. "This is not 2003, but we must not use past mistakes as an excuse for inaction," he said.
There is "no realistic prospect" of defeating ISIS without military action, he said, and Britain has unique assets that no other coalition partner can offer, including precision missiles and surveillance capabilities.
"It is also our duty to take part," he said. "Protecting the streets of Britain is not a task that we are prepared to entirely subcontract to other air forces of other countries."
Last year, Cameron suffered a painful defeat in the Commons when MPs voted against action in Syria in response to claims the Syrian government had used chemical weapons against its own people.
The motion approved by Parliament on Friday specifically rules out action in Syria unless a separate vote is held. It also rules out the use of UK troops in any possible ground combat operations in Iraq.