State Sponsors of Terrorism
One possible definition is the US State Department's List of State Sponsors of Terrorism. The US State Department designation is authorized by three laws: the Export Administration Act of 1979, the Arms Export Control Act, and the Foreign Assistance Act. there are four countries on this list: North Korea, Iran, Sudan and Syria. According to the State Department there are four types of sanctions imposed on countries who are designated state-sponsors of terrorism under these statutes: restrictions on U.S. foreign assistance, a ban on defense exports and sales, certain controls over exports of dual use items; and miscellaneous financial and other restrictions.