The Saudi aviation student responsible for a shooting that killed three U.S. sailors on a Florida base last week appears to have embraced radical ideology as early as 2015, well before he arrived in the United States for training, a Saudi government analysis has found.

According to the internal report, a Twitter account believed to have been used by Ahmed Mohammed al-Shamrani indicates that four religious figures described as radical appear to have shaped the Saudi Air Force trainee’s “extremist thought.” A copy of the report was obtained by The Washington Post.

The attack at Naval Air Station Pensacola has raised concerns about the vetting of foreign military personnel who take part in training and exchange programs in the United States, and it has drawn renewed congressional scrutiny of the kingdom following a period of substantial tension. While some lawmakers have criticized Saudi Arabia for its role in Yemen’s punishing civil war and the killing of journalist and Washington Post contributing columnist Jamal Khashoggi at the Saudi Consulate in Istanbul last year, the Trump administration has consistently defended the kingdom as a key ally against Iran and other threats.

On Tuesday, the Pentagon said it was suspending operational training for about 850 visiting Saudis, part of a larger review of the handling of foreign military students.

Officials have attempted to reassure residents around the base that they are tracking no related plots as they pursue information related to Friday’s attack.

The Saudi government says it is working with the United States and other allies to determine what motivated the shooter and improve screening procedures for military personnel and students being sent overseas.

Officials have scrambled to piece together limited information about Shamrani, who arrived in the United States in 2017 as part of an extended program to become a weapons systems operator. The 21-year-old was shot dead by a sheriff’s deputy after opening fire in a classroom. Eight people were wounded.

The report also put forward information that could explain why his Twitter activity was not previously detected. The account now believed to be Shamrani’s, the report said, did not display his full name, but rather parts of his name that are common in Saudi Arabia, and contained no biographical information or photo.

“Of note, the Shamran tribe is one [of] the Kingdom’s largest tribes, and countless of its members carry the name of Mohammed,” the report said. “As it is not uncommon for extremists and terrorists to use pseudonym of a large tribe to hide their real identity on social media, it was difficult for authorities to properly identify the shooter until he released his manifesto.”

A few hours before the attack, a manifesto was posted on Shamrani’s feed decrying what he said were “crimes against Muslims,” citing the presence of military troops in Muslim nations, the prison at Guantánamo Bay, Cuba, and U.S. support for Israel.

His early Twitter activity, which according to the report began in 2012, when he would have been about 14, revolved mostly around poetry as well as inspirational verses from the Koran.

But later “his tweets and retweets demonstrate his radicalization in late 2015,” the report found, after he began following a series of influential figures, including Saudi nationals Abdulaziz al-Turaifi and Ibrahim al-Sakran, Kuwaiti Hakim al-Mutairi, and Jordanian Eyad Qunaibi.

The two Saudi men were arrested by Saudi authorities in 2016. The report said Mutairi had been accused of links to militants in Syria, while Qunaibi is “described as close to the Salafi-Jihadi movement.” The Post could not immediately verify those characterizations.

The report said Shamrani had retweeted one tweet from Turaifi, who has more than 1 million followers on Twitter, in which the preacher is “decrying the Kingdom of Saudi Arabia’s alliance with the United States whom Al-Turaifi considers ‘the enemy.’ ”

Retweeted tweets from Mutairi, meanwhile, characterized Americans and Israelis as “crusaders” and encouraged “jihad.”

“His retweets and likes in general heavily favored religious accounts that advocated for jihad and defended jihadists who proselytized against both the West and Western-allied Muslim governments alike,” the report said.

A Saudi official cautioned that while the material from Shamrani’s Twitter feed in the report sheds light on his extremist influences, it did not necessarily constitute evidence of what led him to commit the attack.

“Every terrorist is an extremist, but not every extremist commits terrorist acts,” the official said, adding that the kingdom had taken a “zero-tolerance” policy toward extremism as a driver of terrorist violence. “This is very worrying to us. . . . there’s a civil war in our religion and we’re going to have to win it.”

The analysis identified six themes in how Shamrani “at least publicly (online) chose to represent himself and his worldview,” including support for radical Islam and terrorism; support for the Afghan Taliban; “hatred for America and the West;” opposition to the existence of Israel; sectarianism; and rejection of Saudi government reforms.

Souad Mekhennet in Pensacola, Fla., contributed to this report.