•
Bhutan: According to the U.S. State Department, "The United States and the Kingdom of Bhutan have not established formal diplomatic relations; however, the two governments have informal and cordial relations." Informal contact with the nation of Bhutan is maintained through the U.S. Embassy in New Delhi. On April 24, 1981, the Swiss government assumed representation of U.S. interests in
Tehran, and Algeria assumed representation of Iranian interests in the United States. Currently, Iranian interests in the United States are represented by the government of Pakistan. The
U.S. Department of State named Iran a "
State Sponsor of Terrorism" on January 19, 1984. •
North Korea: The Democratic People's Republic of Korea is not on friendly terms with the United States, and while talks between the two countries are ongoing, there is no exchange of ambassadors.
Sweden functions as Protective Power for the United States in
Pyongyang and performs limited consular responsibilities for U.S. citizens in North Korea. •
Syria: On February 6, 2012, the United States suspended operations at its embassy in
Damascus. On May 5, 2014, the United States recognized the
National Coalition of Syrian Revolutionary and Opposition Forces as the
foreign mission of Syria. •
Taiwan: With the
normalization of relations with the People's Republic of China in 1979, the United States has not maintained official diplomatic relations with Taiwan. Relations between Taiwan and the United States are maintained through an unofficial instrumentality, the
Taipei Economic and Cultural Representative Office, with headquarters in Taipei and field offices in
Washington, D.C., and twelve other U.S. cities. The Taipei Office of the
American Institute in Taiwan, a non-profit, public corporation, functions as a
de facto embassy, performing most consular functions and staffed by
Foreign Service officers who are formally "on leave". ==Notable past ambassadors==