The information gleaned by a special team of FBI interrogators before charges were filed against Tsarnaev on Monday appears to be consistent with the direction of a broader investigation that has not uncovered any links to terrorist networks abroad, officials said.
“These are persons operating inside the United States without a nexus” to an overseas group, a U.S. intelligence official said. Instead, officials said, the evidence suggests that Tsarnaev and his 26-year-old brother, Tamerlan, who was killed during a confrontation with police, were “self-radicalized.”
The officials spoke on the condition of anonymity to describe the preliminary findings of an investigation in which information about key aspects of the plot is still being assembled.
U.S. officials briefed on the interrogation of Dzhokhar Tsarnaev said he has specifically cited the U.S. war in Iraq and the campaign in Afghanistan as factors motivating him and his brother in the alleged plot.
Neighbors have also described comments by the Tsarnaevs about the U.S. wars. Albrecht Ammon, 21, of Cambridge said in an interview last week that he had recently argued with the older Tsarnaev about U.S. foreign policy.
Tsarnaev said U.S. wars were based on the Bible, “a cheap copy of the Koran,” Ammon said. Tsarnaev also said that “in Afghanistan, most casualties are innocent bystanders killed by American soldiers,” according to Ammon.
President Obama has made repairing U.S. relations with the Islamic world a foreign policy priority, even as he has expanded drone operations in Pakistan and other countries, inflaming anti-U.S. sentiment among many Muslims.
After attending a classified briefing on the case, senior Republican lawmakers voiced concern that U.S. agencies had failed to share information leading up to the attacks.
“I think there’s been some stovepipes reconstructed,” said Sen. Saxby Chambliss (R-Ga.), the ranking Republican on the Senate Intelligence Committee, using a term that refers to bureaucratic barriers. Chambliss did not provide details.
Sen. Dianne Feinstein (D-Calif.), the chairman of the committee, disputed that characterization and praised the work of investigators, saying she had “complete confidence” the case would be solved.
U.S. officials on Tuesday described several other developments in the investigation into the Tsarnaev brothers’ actions, saying that the suspects may have killed a police officer at the Massachusetts Institute of Technology in an effort to steal his gun and arm themselves after they became the targets of a massive manhunt.