The shooter who killed five Marines in Tennessee on Thursday texted his close friend a link to an Islamic verse hours before the attack, Reuters revealed on Saturday.
According to the report, the verse included the line: "Whosoever shows enmity to a friend of Mine, then I have declared war against him."
The friend thought nothing of it at the time, but now wonders if it was a clue to the rampage in Chattanooga, he told Reuters.
"I didn't see it as a hint at the time, but it may have been his way of telling me something," the friend, who requested anonymity, said of 24-year-old Mohammod Youssuf Abdulazeez.
Abdulazeez, a Kuwaiti-born naturalized U.S. citizen, was killed in a gunfight with police. The FBI is investigating the attack as an act of terrorism, but said it was premature to speculate on the gunman's motive.
While a firm connection between the suspect and radical Islam has not been established, the shooting follows a series of attacks or thwarted attacks in the United States and other countries by Muslims claiming to be inspired by Islamic State (ISIS) or other militant groups.
FBI officials on Thursday night said they don't have "anything that directly ties" the attacker Abdulazeez to any foreign terrorist organizations, although experts have said his behavior fits the mold of attacks Islamic State (ISIS) has called for.
Abdulazeez's friends said he had returned from a trip to Jordan in 2014 concerned about conflicts in the Middle East and the reluctance of the United States and other countries to intervene. The FBI said on Friday it would investigate the visit to Jordan and whether Abdulazeez left Jordan to visit other countries before coming home.
The friends told Reuters that, after the trip to Jordan, Abdulazeez purchased three assault rifles on an online marketplace and used them for target practice.
"That trip was eye-opening for him. He learned a lot about the traditions and culture of the Middle East," said the close friend who received the text message.
Abdulazeez was upset about the 2014 war between Israel and Hamas in Gaza and the civil war in Syria, he said. "He felt Jordan, Qatar, Saudi Arabia were not doing enough to help, and that they were heavily influenced by the United States."
Another friend said, "He had always talked about it, but I'd say his level of understanding and awareness really rose after he came back."
According to Abdulazeez's friends, he had purchased three guns via the internet after returning from Jordan, including an AK-74, an AR-15, and a Saiga 12. They said he also owned a 9mm and a .22 caliber hand guns.
It was previously revealed on Friday that Abdulazeez's father was investigated several years ago for donating money to an organization possibly connected to a foreign terrorist organization.
The father was on a terrorist watch list and even questioned during a trip out of the country, but eventually his name was taken off the terrorist list.
The attack on an army site brings to mind the 2009 shooting attack at the Fort Hood army base, when Palestinian American Army Major Nidal Hasan unleashed a deadly shooting rampage, murdering 13 and wounding 32. Hasan admitted to conducted the shooting as an Islamist terror attack.
The same base was targeted again in April 2014, with the shooter and three victims killed as well as 14 wounded.