US President Donald Trump has approved the execution by firing squad of Nidal Malik Hasan, the former US Army psychiatrist convicted of killing 13 people at Fort Hood in Texas in 2009.
The Pentagon announced the decision on Monday, saying Defence Secretary Pete Hegseth had recommended the method and Trump had approved it.
Pentagon spokesman Sean Parnell said the Secretary of the Army would determine the time and location of the execution.
Hasan was sentenced to death by a military jury in 2013 after being convicted of the mass shooting at Fort Hood, now known as Fort Cavazos. The attack also left more than two dozen people wounded.
His execution would be the first carried out by the US military since 1961.
Hasan, a US-born Muslim of Palestinian descent, opened fire on November 5, 2009, at a medical facility at Fort Hood, a major US Army installation used by troops preparing for deployments to combat zones.
Twelve of those killed were soldiers, while 30 of the wounded were also members of the military. Hasan was shot and wounded by a civilian police officer who responded to the attack. The officer was left partially paralysed.
During his court martial, evidence showed that Hasan opposed US military operations in Iraq and Afghanistan. He had also communicated online with Anwar al-Awlaki, an American-born radical cleric linked to Al-Qaeda who was later killed in a US drone strike in Yemen.
Hasan represented himself during his trial, calling no witnesses and giving no testimony. He did not deny the charges, while his court-appointed lawyers raised concerns that he wanted to be executed.
The Pentagon’s announcement brings Hasan’s long-running death sentence closer to being carried out, pending the military’s scheduling of the execution.