A military jury has sentenced US army major Nidal Hasan to death by lethal injection for killing 13 people and wounding 31 others in a November 2009 shooting rampage at Fort Hood in Texas.
The jury of 13 officers deliberated for a little more than two hours before deciding the sentence for the army psychiatrist.
Hasan admitted to being the gunman and said he had switched sides in what he considered to be a US war on Islam.
The US military last executed a prisoner in 1961.
Bearded and in a wheelchair, Hasan showed no visible expression as the president of the jury read aloud the sentence that he "be put to death".
He is paralysed from being shot by police trying to end the rampage.