28 August 2013 Last updated at 23:38 GMT
It could be years, possibly decades, before Maj Hasan is executed because of the long appeals process in the military justice system.
A military jury has sentenced a former US Army psychiatrist to die by lethal injection for killing 13 soldiers and wounding 32 at a Texas Army base.
Maj Nidal Hasan, 42, was convicted last week of the November 2009 shooting rampage at Fort Hood.
The defendant had tried to admit his guilt but military law bans guilty pleas in death penalty cases.
The Virginia-born Muslim said he opened fire to protect Taliban insurgents from troops about to deploy to Afghanistan.
‘Never a martyr’
At the scene
Alastair Leithead BBC News, Los Angeles
Maj Nidal Hasan sat in his wheelchair and gave no reaction to the death sentence.
The Army psychiatrist had listened to the prosecutor go through the personal stories of each of the 13 people he killed.
He had seen their photographs as the jury heard about the impact his actions had on the parents, widows and children left behind.
The prosecutor described the way each family member of each soldier killed was visited by “two soldiers in Class A uniforms” knocking on the front door with death notifications.
Hasan shut his eyes occasionally, rubbed his unkempt and greying beard, and held his head in the one hand he is still able to use after being paralysed by the shots which stopped his shooting rampage.
And he again declined his final opportunity to offer an explanation for what he did.
The jury handed down its sentence after two hours of deliberations on Wednesday.
But it could be years, possibly decades, before Maj Hasan is executed because of the long appeals process in the military justice system.
His execution must eventually be authorised by the president.
On Wednesday before the sentence was handed down, prosecutor Col Mike Mulligan urged jurors to opt for a rare military death penalty.
“He will not now and he will never be a martyr,” Col Mulligan said of Maj Hasan. “He is a criminal. He is a cold-blooded murderer.”
“This is not his gift to God. This is his debt to society. This is the cost of his murderous rampage.”
“He will never be a martyr because he has nothing to give,” Col Mulligan added. “He will not be giving his life, we will be taking it.”
Maj Hasan, who represented himself, declined to speak on his own behalf, saying only: “I have no closing statement.”
The 13-member jury had to reach unanimous agreement in order to sentence Maj Hasan to death, otherwise he would have faced life in prison.
The US military has not executed a service member since 1961. There are five inmates on the US military’s death row at Fort Leavenworth, Kansas, all at various stages of the appeals process.
Maj Hasan opened fire at a medical facility on the Fort Hood base where soldiers were being evaluated before deploying overseas.
The jury heard he had prepared carefully for the attack, during which he fired 146 bullets.
The shooting spree ended when he was shot by a civilian police officer.
He was paralysed from the waist down and now uses a wheelchair.