Some economic sanctions imposed by the United States in recent years to protest invasions, anti-American policies and links to international terrorism: Libya 1986 -- Assets frozen after accusing Moammar Gadhafi of supporting international terrorism. Other sanctions still in place include bans on trade, loans to the Libyan government and travel to Libya by U.S. citizens. Soviet Union 1979 -- Export restrictions after the invasion of Afghanistan. 1981 -- Sanctions imposed against Poland and the Soviet Union after government actions were taken against Solidarity. Later relaxed in 1983 and 1984, sales of high technology to Moscow are still restricted. Panama 1988 -- Reagan puts payments for operation of the canal in escrow and tax payments by U.S. organizations to the Noriega regime are prohibited. China Bans on military sales and blocks against international loans after military crackdowns on pro-democracy demonstrations. South Africa Bans on the sales of computer equipment used to enforce Apartheid, most nuclear technology, and the import of gold coins. Iraq 1979 -- Restrictions of high technology and military equipment, lifted in 1982. 1984 -- Sales of chemicals needed to manufacture chemical weapons blocked. 1988 -- Congress votes similar measures after alleged use of poison gas against Kurdish rebels. 1990 -- Assets in U.S. blocked after invasion of Kuwait. Iran 1979 -- Assets frozen after seizure of U.S. Embassy and 50 Americans taken hostage. Countries without diplomatic relations with the U.S. are subject to trade sanctions. They include: North Korea, Cuba, Albania and Vietnam.