A Cardiff jihadist who was one of three men from the city to have joined a group in Syria was killed by the RAF.
Reyaad Khan, 21, died on 21 August, along with another man, in a "precision airstrike" in Syria, the Prime Minister David Cameron said on Monday.
He said Khan was plotting "barbaric" attacks on UK soil and he was killed in an "act of self-defence".
The jihadist's death was first announced at the Jalalia mosque in Riverside.
It is the first time an RAF drone has been used to attack a British national in a country in which it is not at war.
Addressing MPs, Mr Cameron said: "Both Junaid Hussain and Reyaad Khan, were British nationals based in Syria who were involved in actively recruiting ISIL sympathisers and seeking to orchestrate specific and barbaric attacks against the west including directing a number of planned terrorist attacks right here in Britain, such as plots to attack high profile public commemorations, including those taking place this summer.
"We should be under no illusion, their intention was the murder of British citizens, so on this occasion we ourselves took action.
"In an act of self-defence, and after meticulous planning, Reyaad Khan was killed in a precision airstrike on 21 August by an RAF remotely operated aircraft while he was travelling in a vehicle in the area of Raqqa in Syria."
Following the announcement in the Commons, Cardiff West MP Kevin Brennan said Khan's death was a "sad inevitability".
"But the house will have been surprised to find that the manner of his death has been by a drone strike against a British citizen in Syria and therefore there will be many questions that the house will have, and I will have as his constituency MP," he added.
'Got to take action'
Mr Brennan said he wanted Mr Cameron to explain the "nature of the threat" Khan posed.
The PM responded he would be as "forthcoming as I possibly can be".
He added: "When we're dealing with people who are producing such a tempo of potential terrorist attacks - attacks on police, attacks on members of the armed services attempted attacks on commemorations in our own country... we've got to take action... there's no other way of dealing with it than the route that we took."
Family friend Mohammed Islam said it was "shocking" news for the Riverside community where Reyaad Khan grew up.
Last year, former Cantonian High School and St David's College student Reyaad Khan appeared in a video along with another man from Cardiff urging others to join so-called Islamic State.
He was seen in the 13-minute IS propaganda video in June 2014 alongside his friend Nasser Muthana, also from Cardiff, and Abdul Raqib Amin from Aberdeen.