An audio recording purporting to be from the Al-Qaeda in the Arabian Peninsula (AQAP) terrorist organization claimed responsibility on Sunday for the December attack at a US naval base in Pensacola, Florida, but provided no evidence.
"We congratulate our Muslim nation and embrace the operation of the martyr hero, the daring knight Muhammad bin Saeed Al-Shamrani," said the audio, released by Al-Qaeda’s Yemen branch and quoted by Reuters.
Reuters was unable to verify the authenticity of the recording.
Three people were killed in the shooting, which US Attorney General William Barr said last month was an act of terrorism motivated by "jihadist ideology".
The attacker, 21-year-old Mohammed Alshamrani was a member of the Royal Saudi Air Force who was training at Naval Air Station Pensacola. He entered a building on base and "proceeded to walk around shooting down his unarmed victims in cold blood," Barr said at a press conference.
Alshamrani, who was killed by law enforcement during the attack, had a history of airing his anti-American, anti-Israel and jihadi messages views on social media, including in a post on September 11 stating that "the countdown has begun," and another post made two hours before the attack, Barr said.
The FBI had said immediately after the shooting it is believed the shooter acted alone and that motive for the shooting was not yet established, though it added it was working, as it does in most mass shootings, on the presumption that it was an act of terrorism.
AQAP has carried out many terrorist attacks in Yemen in recent years and has also targeted the West, having in 2015 claimed responsibility for the Charlie Hebdo killings in Paris and then calling for “lone wolf attacks” against Western targets.
The leader of AQAP, Nasser al-Wuhayshi, was killed in an American air strike in June of 2015.