The UK has launched its first air strikes in Syria, hours after MPs overwhelmingly endorsed Prime Minister David Cameron's plan to bomb what he called the "medieval murderers" of Isis.
Four Tornado jets took off from the RAF's Akrotiri air base in Cyprus and struck targets in Syria early on Thursday morning.
Michael Fallon, UK defence secretary, told the BBC the strikes targeted oilfields and well heads in eastern Syria. The four Tornados left the base in pairs around 03.00 GMT, with two returning without their 500lb Paveway bombs.
Mr Fallon added that the RAF force in Cyprus would be doubled, with two extra Tornados and six Typhoon jets already on their way.
The US-led coalition, which has been carrying out strikes against Isis in Syria for months, has recently turned its attentions to oil infrastructure in territory controlled by the group.
Oil is one of the main revenue sources for Isis, or Daesh, as the UK government now refers to the group. Isis generates millions of dollars each week by selling oil on the black market to buyers within the country, including some of its military opponents, and overseas.
"This strikes a very real blow at the oil and the revenue on which the Daesh terrorists depend," said Mr Fallon.
Sir Michael Graydon, former chief of the air staff, has told the BBC the targets of the air strikes will have been carefully identified.
"The sort of targets that they've attacked, as I understand it on this occasion, will be very clear. There should be no doubt that these will be oil installations," he said.
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"Tanks, various logistics sort of places, will be on a target list — long identified and relatively easy to identify."
The French president's office said it welcomed the British decision to join the air campaign in Syria. France has called on its European allies to add their resources to the fight against Isis in the wake of the Paris attacks last month.
As the UK debated whether to launch strikes on Wednesday, German ministers backed a plan to commit up to 1,200 soldiers to the military efforts against Isis. The proposal will need approval from the Bundestag.
The British strikes came just hours after the House of Commons approved the extension of military action against Isis into Syria from Iraq, where UK jets have been operating for more than a year.
However, Conservative MP John Baron, who voted against the motion on Wednesday night, reiterated his concerns about an "absence of strategy" and the "fact that there is no exit strategy".
Speaking on BBC Radio 4, he said that claims the bombings would guarantee UK involvement in diplomatic efforts to end the Syrian civil war were false. "We're already at the top table," he said.
Mr Baron was one of seven Tory rebels, but with the backing of 66 Labour party MPs, and the Liberal Democrats, the motion passed with a majority of 174. The vote followed a long and impassioned day of debate in parliament, including a memorable speech by shadow foreign secretary Hilary Benn in support of strikes.
John McDonnell, the shadow chancellor and a close ally of Labour leader Jeremy Corbyn, who voted against the motion, applauded the quality of the debate but said: "Sometimes the greatest oratory can lead to the greatest mistakes. That's what it did in Iraq."