Unlike people from Iraq, Somalia and other hotbeds of strife, however, very few displaced Chechens resettled in the U.S., despite the fact that the decade of conflict caused 350,000 Chechens to flee from their homes.

So why are there so few Chechens in America? Mainly, because we don't resettle Chechen refugees here.

There are two primary ways to make it into the U.S. if you have the misfortune of living in a war zone or an especially repressive country: You can become a refugee, which is someone who still lives abroad, or an asylum seeker, which is someone who has managed to make it either inside the U.S. or to a port of entry.

Each year, the U.S. resettles about 50,000 refugees -- individuals who are thought to face extreme danger in their home countries. At the moment, the top countries of origin for refugees to the U.S. are Burma, Bhutan, and Iraq. In all, the U.S. allows in up to 80,000 refugees, and most of those slots are allocated to the Middle East and South Asia. Europe and Central Asia, where Chechnya is located, get the smallest tranche -- just 2,000 spaces.

After 9/11, it became much more difficult to resettle individuals from countries where Islamists movements are taking root -- as appears to be the case in Chechnya -- because of stricter security screenings.

And frankly, says Kathleen Newland, director of refugee programs at the Migration Policy Institute, the Chechen population was never of "special concern" to the United States, and the hope was that the region's displaced citizens would return home when its wars ended.

Meanwhile, foreigners who are already in the United States -- either illegally or on some sort of temporary visa -- can apply for asylum, which means that if their application is accepted, the U.S. government won't send them back, for fear of persecution in their homelands. In 2011, 25,000 such people were granted asylum, with most coming from China, Venezuela, and Ethiopia.

This asylum process is how the suspects' father, Anzor Tsarnaev, a Chechen man who was living in Dagestan in southern Russia, ended up in Boston: He and his then-8-year-old son Dzhokhar, the surviving suspect, arrived in the U.S. legally in 2002 on a tourist visa, and then petitioned to stay as asylum seekers.

Most Chechens haven't tried to gain asylum, according to Newland, because it's prohibitively expensive for them to get to America, and there are so few Chechens here that it can be hard for newcomers to find communities of support. What's more, the European Union is much nearer and is an attractive destination for Chechen asylum seekers -- a 2009 estimate found that there were 130,000 Chechen exiles living in Europe.

I asked Newland if the U.S. had perhaps been reluctant to admit Chechen refugees and asylum seekers over the years in order to play nice with Russia, Chechnya's sworn foe. Newland says that's not the case. Throughout the 80s and early 90s, the United States admitted thousands of Russian Jews and evangelical Christians as refugees even as the Soviet Union claimed that religious minorities did not face discrimination there. And in 2004, the U.S. granted asylum to a high-ranking Chechen separatist, Ilyas Akhmadov, despite Russia's claims that he was a "terrorist."