Britain has killed two of its own nationals accused of fighting for the Islamic State of Iraq and the Levant (ISIL), and plotting attacks on British soil, in its first air strike in Syria, Prime Minister David Cameron announced.
Despite not having a parliamentary mandate to take military action in Syria, Cameron told politicians on Monday that, as an act of self-defence, Briton Reyaad Khan had been targeted and killed in a precision drone strike in the country.
Cameron said the strike was carried out by a British Royal Air Force (RAF) remotely piloted aircraft in August and that two people travelling with the man, including another Briton, Ruhul Amin, were also killed.
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"There was a terrorist directing murder on our streets and no other means to stop him," Cameron said. "We took this action because there was no alternative."
The strike was approved by the attorney general - the main legal adviser to the UK, said Al Jazeera's Emma Hayward, reporting from London.
"This strike on Reyaad Khan will be seen as controversial - not least because of the grey area surrounding the legality of crossing the line and carrying out a strike in Syria."
Khan, from the Welsh capital Cardiff, and Amin, from Aberdeen in Scotland, had their assets frozen by Britain's finance ministry last year after reports they had been involved in terrorism-related activities in Syria and appeared in an ISIL recruitment video.
"There was clear evidence of the individuals in question planning and directing armed attacks against the UK," Cameron said.
A third Briton fighting with ISIL, Junaid Hussain, was killed in a separate US air strike in August, Cameron said.
Cameron said both Khan and Hussain had been involved in "plots to attack high profile public commemorations, including those taking place this summer".
Remote-controlled summary killings
Amnesty International's UK Director Kate Allen said it was "extremely alarming that the UK has apparently been conducting summary executions from the air.
"In following the United States down a lawless road of remote-controlled summary killings from the sky, the RAF has crossed a line," she added.
British warplanes have launched regular air attacks against ISIL in Iraq in recent months and flown drones over Syria to gather military intelligence. But unlike some countries in a US-led international coalition, it does not generally target ISIL in Syria.
The Royal United Services Institute (RUSI) think-tank said the strike marked a big departure in policy.
"The point is not so much that this man was British but that he was targeted in an area that the UK does not currently regard, legally, as an operational theatre of war for UK forces," said RUSI Director General Michael Clarke in a statement.
In 2013, Cameron suffered a humiliating defeat in parliament when he sought approval of possible military action against Syrian President Bashar al-Assad.
Source: Al Jazeera and agencies