As investigators sought to decipher the motives of the gunman who targeted U.S. troops in Chattanooga, Tenn., they also began to confront the uncomfortable question of whether counterterrorism agencies are reaching the practical limits of what they can do to detect homegrown plots.
On Friday, federal officials said they were investigating the Chattanooga shootings as a possible terrorist attack but were a long way from drawing conclusions. They said the gunman, 24-year-old Mohammad Youssef Abdulazeez, had not previously drawn the attention of authorities, save for a drunken-driving charge a few months ago.
But Abdulazeez’s travels to the Middle East, his acquisition of multiple firearms and his recent online musings about the meaning of Islam were coming under fresh examination as hundreds of federal agents sought to reconstruct his movements and mind-set.
“At this time, we have no indication he was inspired by or directed by anyone other than himself,” Edward Reinhold, the special agent in charge of the FBI’s office in Knoxville, Tenn., told reporters Friday.
U.S. officials said devices, including a computer and cellphone, believed to have belonged to Abdulazeez were being examined by FBI technicians in a laboratory at Quantico, Va.
The FBI said Abdulazeez was armed with at least two rifles or shotguns, as well as a handgun, when he opened fire on a military recruiting center and a Navy Reserve facility in Chattanooga. Authorities did not give a more detailed description of the firearms or say how he obtained them.
“Some of the weapons were purchased legally, and some of them may not have been,” Reinhold said.
U.S. counterterrorism officials have become increasingly worried about the ability of the Islamic State and al-Qaeda offshoots to attract and radicalize followers in the United States. At the same time, authorities have expressed concern that their ability to detect such contact has been eroded by the spread of encrypted communication.
Federal authorities have arrested more than 10 people in the past six weeks who are suspected of having ties to the Islamic State. U.S. officials said the crackdown was part of an effort to suppress a surge in suspected plots aimed at unleashing violence on U.S. targets during the Muslim holy month of Ramadan, which ended on the day of the attacks in Chattanooga.
But officials also have said homegrown radicals have gotten better at hiding their intentions and cloaking their contacts with overseas groups, despite a massive expansion in U.S. surveillance capabilities since the Sept. 11, 2001, attacks.
Abdulazeez traveled to Jordan last year and remained abroad for several months, according to U.S. officials, who said his travels at the time did not raise red flags. Jordan has been a way station for foreign fighters seeking to enter Syria, including a 22-year-old U.S. citizen who similarly went undetected during trips to Jordan before carrying out a suicide attack in Syria last year.
But Jordan is also a popular tourist destination, one of several nations bordering Syria that account for more than 2 million travelers who arrive in the United States each year.
Moreover, Abdulazeez had a grandmother and other relatives in the country, according to neighbors and court papers.
And while his father, Youssuf Abdulazeez, was investigated by the FBI in 1994 and 2002 for donating to Palestinian groups suspected of ties to terrorism, U.S. officials said the father was removed from a watch list a decade ago.
Based on the limited information available so far, the younger Abdulazeez appears repeatedly to have brushed up against U.S. screening systems without ever triggering an alert.
