The British Muslim community is demanding evidence that Reyaad Khan from Cardiff, who had gone to Syria to fight with Isis, was planning attacks on the UK.
The 21-year-old Briton was killed in a drone strike on 21 August by the RAF and was targeted for plotting attacks on British soil, according to UK Prime Minister David Cameron. Ruhul Amin, another jihadi from Aberdeen also died when Khan, the main target was killed. Junaid Hussain from Birmingham was killed three days later by a US drone in a joint operation with the UK.
The strike is the first time a British prime minister has authorised the targeting of a UK citizen by unmanned aerial drone outside a formal conflict.
Saleem Kidwai, the secretary general of the Muslim Council of Wales said: "I hope the evidence is much stronger than with the weapons of mass destruction."
He described Khan as a "bright boy" who once dreamed of becoming the UK's first Asian prime minister, The Guardian reports. "He was a normal child. What happened, God knows."
He is not convinced about the evidence of terror plots in the UK, as claimed by Cameron. "We are not convinced because he was not the kind of charismatic person who could control something like this from far away."
"As news spread around the community the questions are being asked, what information did the intelligence or the government have," he said, according to the Daily Mail.
Mokaddus Miah, the Secretary of the Jalalia mosque in Grangetown, Cardiff said: "If a person has done something bad then he has what's coming to him. Anyone who wants to do something wrong must be punished. But I would have preferred to see him tried in a British court."
Mohamed Islam, a family friend of Khan urged Cameron to reveal "the truth of this incident. It's a devastating situation for us as a local community. In the coming days and months members of the public would like more details."
The former city councillor told the BBC: We are very shocked and devastated to hear that a British prime minister for the first time ever in history went out of the country ... and go and kill a British citizen without any legal permission from the parliament."
"What is so serious that he [Khan] is going to do something from Syria and our M16 and M15, and the whole defence in the British system, are completely going to fail a single Reyaad Khan? This is completely surprising me and shocking me that the whole country and the defence system is failing [those] jihadists. This is a cover-up story, I believe," Islam says.
A member of the Jalalia mosque who only wanted to be known as Shamsu, told the Daily Mail: It makes it worse because it's like your own country that's killed you. But they [the government] should have stopped him before he even got there because he's a child at the end of the day and he's been manipulated."
The Welsh nationalist party, Plaid Cymru has asked for more information on the intelligence that led to the British strike. "The killing of a UK citizen abroad in the territory of another sovereign state, and by this method is unprecedented, on the government's own admission. The prime minister must explain the justification and legal basis behind his decision," the party's defence and foreign affairs spokesperson Hywell Williams MP said.
"He should set out the nature of the imminent threat he claims this individual posed. He should also publish the attorney general opinion."
Neighbours mixed on Reyaad's killing
Roofer Steve Leyshon, 32, told the Daily Mail: "He had what was coming to him. He threatened us so we killed him. I feel sorry for his parents - but I don't want to feel sorry for any parents of any British people he wanted to kill."
Another neigbour, Pete Kaminski, 52 however had different views. "I'm not happy that we killed a British boy like that. We should have brought him to justice not execute him. In this country we pride ourselves on being just, democratic and moral. I'm not comfortable that we can just blow a young man up from out of the skies."