It took only hours after the identities of the two suspects in the Boston Marathon bombing were revealed for some politicians and commentators to suggest that the tragedy was somehow the fault of a broken immigration system.
Ever since September 11, there has been a strong and understandable desire for a perfect screening system for would-be immigrants. If only the United States could put that system into place, bad people would never be admitted to the country. But such perfection is unachievable, and would not have prevented the Boston attacks. It would be a further tragedy to allow sensible overhaul of the U.S. immigration system to be derailed by such misperceptions.
Here's what we know so far. The two brothers suspected in the bombings, Dzhokhar Tsarnaev, 19, and Tamerlan Tsarnaev, 26, were brought to the United States by their parents in 2002, likely from the former Soviet Republic of Kyrgyzstan. That means one was a child and the other in his early teens when they moved to Boston.