From this:

In the three fiscal years from 2007-2009, the Department of Homeland Security caught and released 481 illegal aliens from nations designated as state sponsors of terrorism and “countries of interest,” and those 481 aliens are now fugitives, according to an Immigration and Customs Enforcement database obtained by CNSNews.com as the result of a Freedom of Information Act request.

The four state sponsors of terrorism, as determined by the State Department, are Iran, Syria, Sudan and Cuba. The “countries of interest” are those additional countries whose citizens have been subjected to enhanced screening on U.S.-bound flights by the Transportation Security Administration as a result of the attempted Christmas Day bombing of Northwest Flight 253.

Note that all but about eight months of that three year period were under the George W Bush administration.