CAIRO — Al Qaeda in the Arabian Peninsula claimed on Sunday that it directed a Saudi military officer to carry out the shooting at a United States military base in Florida in December that killed three sailors and wounded eight people.
In an audio recording released on Sunday, the leader of the Yemen-based group, Qassim al-Rimi, claimed responsibility for the Dec. 6 attack at Naval Air Station Pensacola, according to SITE, an organization that tracks jihadist media.
The group offered no evidence that it had trained the gunman, Second Lt. Mohammed Saeed Alshamrani, but produced a copy of his will as well as correspondence that indicated he had been in contact with Al Qaeda. Experts said those elements gave the claim a plausible air.
Mr. al-Rimi, the Qaeda leader, may himself be dead. He was the target of an American drone strike in eastern Yemen last week, according to American and Yemeni officials who said they believed he had been killed but were awaiting confirmation.
On Saturday, President Trump fueled speculation that confirmation had been received when he retweeted several messages and a media report about Mr. al-Rimi’s death.
The 21-year-old Saudi Air Force trainee who carried out the Pensacola attack was not a known member of Al Qaeda. A sheriff’s deputy shot him dead during the attack, and his family in Saudi Arabia said it was mystified by his actions.
But F.B.I. investigators have said they were following leads that Mr. Alshamrani had been influenced by extremists as early as 2015. And on Sunday, Al Qaeda provided a purported copy of a last will written in September.
The group also cited from correspondence with the young Saudi officer, in which he described his life on the American base.
“The program is called Aviation Preflight Introduction,” one letter read. “I started with the running tests last Friday and I passed them, thank God. On Monday the swimming tests will start for a week, followed by five weeks of academic tests.”
At a news conference last month, the F.B.I. deputy director, David Bowdich, said that while Mr. Alshamrani did not appear to be motivated by one specific terrorist group, he harbored anti-American and anti-Israeli views. His social media comments echoed those of Anwar al-Awlaki, the radical Yemeni-American cleric and senior leader of Al Qaeda in the Arabian Peninsula who was killed in a drone strike in 2011, Mr. Bowdich said.
On Sunday, SITE said that Mr. Alshamrani posted a short manifesto on Twitter before the attack that read: “I’m against evil, and America as a whole has turned into a nation of evil.” The Twitter account has been suspended.
“The timing of this audio is designed to cause maximum humiliation for Trump, who had just retweeted reports of al-Rimi’s death,” said Bruce Riedel, a scholar at the Brookings Institution and a former C.I.A. officer. “It’s also a statement that AQAP has infiltrated the Saudi military, which is an embarrassment for the Saudis.”
Colin P. Clarke, a senior fellow at the Soufan Center, a New York-based research organization, said that Al Qaeda’s claim to have directed Mr. Alshamrani could well be legitimate.
“This makes the F.B.I.’s battle with Apple for access to Alshamrani’s phone even that much more critical,” he said, referring to a dispute over Apple’s refusal to unlock the shooter’s iphone.
Mr. al-Rimi, 41, led a potent branch of Al Qaeda that, despite some serious setbacks in recent years, still harbored ambitions of carrying out attack in the United States and Europe.
In 2018, the United States doubled a reward for information about Mr. al-Rimi’s whereabouts to $10 million. The C.I.A. picked up his trail in November, officials told The New York Times last week.
He had been considered a potential successor to Ayman al-Zawahri, the overall leader of Al Qaeda, said Rita Katz of SITE.
Last month, the United States Justice Department said it was sending home 21 Saudi students from the Pensacola base after they were found to be in possession of jihadist material or pornography.
Attorney General Bill Barr said the Saudi government had undertaken to review each case under its code of military justice. Pornography is forbidden in the kingdom.
Reporting was contributed by Eric Schmitt in Washington, Saeed al-Batati in Al Mukalla, Yemen, and Nada Rashwan in Cairo.