New Delhi, Dec. 14 -- US President Donald Trump has said the United States "will retaliate" after three Americans were killed in a suspected Islamic State (IS) attack in Syria. This is the deadliest assault on US personnel in the country since the fall of former president Bashar al-Assad a year ago.

Two US service members and a civilian interpreter were killed, while three others were wounded in an ambush on Saturday (December 13) carried out by a lone gunman, according to the US military's Central Command.

"This is an ISIS attack," Trump told reporters at the White House before departing for the Army-Navy football game in Baltimore.

Trump offered condolences to the families of those killed and said the injured were recovering.

"We mo...