On December 29, 1979, the United States of America first published a list of states that, in the opinion of the US State Department, support international terrorism. Since then, this list is updated annually. Initially, the list of terrorist countries included Libya, Iraq, South Yemen, and Syria. To date, the list is almost completely changed.

North Korea

North Korea was a designated state sponsor of terrorism from 1988 until 2008 when then-US President George W. Bush removed it from the list in an attempt to facilitate a dialogue on reducing Pyongyang's nuclear capabilities. That attempt proved futile.

In the latest move in an ongoing diplomatic crisis between the United States and North Korea over the latter's growing nuclear arsenal, North Korea was placed back on the US Department of State's State Sponsors of Terrorism list on November 20.

Syria

Syria has been on the blacklist since the designation was created in 1979. According to the U.S., Bashar Assad's regime supports a variety of terrorist groups that have a destabilizing effect well beyond the region. In particular, according to the U.S., it provides political and weapons support to Lebanon-based Hezbollah while helping Iran to keep the group armed.

The U.S. claim against Syria also includes concerns about weapons of mass destruction — according to the State Department, it has used chemical weapons repeatedly against its own people.

Iran

Iran's listing goes back to 1984. A State Department report in July called Iran the world's foremost sponsor of terrorism and said it has supported Shia militias in Iraq and attempted to smuggle weapons to Palestinian terrorist groups in Gaza. The WMD issue, also a factor with North Korea and Syria, has been cited by the State Department regarding Iran because of the proliferation threat posed by its nuclear program.

Sudan

This East African nation made the blacklist on August 12, 1993. But along with the terrorism links, and a president who is wanted by the International Criminal Court on genocide charges, the State Department has asserted that Sudan's government flouts the rule of law and lets its security forces commit abuses with impunity.

The U.S. government, however, has recently credited Sudan with some improvements. Just before leaving office, Obama issued an executive order that lifted decades-old sanctions on a probationary basis. Trump formalized that last month and is reportedly willing to delist Sudan if improvements continue.