Hasan, a US Army psychiatrist from Virginia, carried out the deadliest non-combat attack on an American military base on 5 November 2009 at Fort Hood, Texas. He fatally shot 13 soldiers in a crowded medical building where deploying troops were awaiting check-ups and vaccines, and injured 32 others. During his 2013 court-martial, Hasan admitted to being the gunman and apologised for "any mistakes", stating he believed he was protecting Muslims and the Taliban in Afghanistan.
Parnell wrote on X: "Judgement day for Hasan has finally come." Hasan is currently one of four inmates on the US military's death row.
Military executions require presidential approval under military law, along with appellate review and a final judgment on legality. The US Court of Appeals for the Armed Forces deemed the military death penalty unconstitutional in 1983, but it was reinstated the following year by an executive order under then-President Ronald Reagan.
Death by firing squad is uncommon in the United States. The last such execution at a state level occurred in South Carolina last year — the first use of the method in the US in 15 years. Four other states — Idaho, Mississippi, Oklahoma and Utah — also allow firing squads.
The majority of US executions are carried out at the state level, with 27 states, the federal government and the military retaining capital punishment as a legal option.