Fiona Hill, a Caucasus specialist at the Brookings Institution think tank, said the conflict in Chechnya is used as a recruiting tool for Al-Qaeda.
"Videos from Chechnya are all over the Internet. They're constantly packaged as part of the Al-Qaeda network recruitment," she said.
Dzhokhar used Twitter and VKontakte -- the Russian equivalent of Facebook -- where his profile identifies "Islam" as his world view, lists information about Chechnya and Islam, and relates jokes about the unfair treatment of Muslims in the Caucasus.
Ben Wittes, an expert on terrorism and national security at Brookings, said the attack in Boston could be construed as domestic but have international resonance.
"The difference is really a question of who, if anyone, the Boston suspects were really in touch with and who, if anyone, may have been directing what they were trying to do and successfully did," Wittes said.
The Fort Hood shootings in 2009, where US Army Major Nidal Malik Hasan is accused of killing 13 soldiers and military support personnel, unfolded in a similar gray area between domestic and international militancy.
Hasan, born in the United States to Palestinian parents, was said to have had contacts with Anwar al-Awlaqi, the American-born radical cleric later killed in a US drone strike in Yemen.
Frank Cilluffo, director of the Homeland Security Policy Institute at George Washington University, said there were many examples of people wanting to fight for Al-Qaeda in their own country.
"Specifically, you've had a number of examples and cases where people who were trying to fight overseas have been turned back around to attack their homeland," he added.
The bombs used in Boston, pressure cookers filled with explosives, reflect the methods advocated by Inspire, the English language magazine published by Al-Qaeda in the Arabian Peninsula, the movement's Yemeni offshoot, which has also urged aspiring jihadists to launch attacks in their own countries.
Brian Jenkins, author of a Rand study on the profile of jihadists in the United States, said 74 percent of those involved in such plots were American citizens, of which 49 percent were born here and 29 percent were naturalized.
"Many of the jihadists identified in the cases discussed here began their journey toward radicalization on the Internet where they found resonance and reinforcement for their frustration and anger," he wrote.
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