With which countries are FCC-licensed amateur radio stations prohibited from exchanging communications?

The International Telecommunication Union (ITU) is the United Nations specialized agency that coordinates global telecommunication standards. According to international treaties, if a country's government formally notifies the ITU that it objects to amateur radio communications, amateurs in other countries must respect that ban. The distractors mention the ARRL or IARU, but these are amateur radio organizations, not government regulatory bodies. Only a country's sovereign administration, acting through the official channel of the ITU, has the legal authority to prohibit these communications.