The trade sanctions against Nicaragua announced yesterday are the latest in a series of special trade, travel and financial restrictions the United States has imposed against other nations. With the addition of Nicaragua, restrictions are now in force against 11 nations.

North Korea holds the distinction of being the target of restrictions in force for the longest time, since December 1950, soon after its troops invaded South Korea. The restrictions bar both exports and imports, financial transactions and travel, athough there are exceptions.

Similar restrictions are in place against Cuba (since July 1963), Vietnam (May 1964) and Cambodia (April 1975).

The curbs against Nicaragua are not as severe, since there is no ban on travel or financial transactions.

Libya has been targeted for special curbs because of its policies of "aggression, subversion and support for terrorism," the State Department reported. In December 1981, the Reagan administration declared that U.S. passports are no longer valid for travel to Libya, although the State Department said some American citizens still work there in defiance of the ban. It is possible, moreover, to get a special passport validation to visit Libya.

A special exception is made for U.S. journalists to visit countries such as North Korea, Cuba, Vietnam, Cambodia and Nicaragua.

Exports to Libya of any U.S. products, from high technology to household appliances, require a special license. These are generally given freely for products such as refrigerators, but refused for anything involving national security. In March 1982, a ban was placed on imports of Libyan crude oil.

Foreign policy controls were placed on four Mideast nations -- Iran, Iraq, South Yemen and Syria -- limiting shipments of such potential military supplies as aircraft, aircraft parts and helicopters above a certain weight, in a U.S. effort to promote regional security.

In addition, Iran, South Yemen and Syria are on a special list of countries with trade curbs because they promote terrorism. Iraq had been on that terrorism list, but the State Department said it has been removed.

South Africa faces special bans on the sale of high-technology equipment, especially computers, that can enhance its nuclear program. There are, moreover, curbs on any sales to its police and military and to the four agencies that administer apartheid, the separation of the races.