Reagan's programs are not as numerous, but sources say they sometimes surpass in magnitude those undertaken in the CIA's golden age of covert operations, which ended by disclosures and congressional investigations of such CIA operations as assassination plots against Cuban President Fidel Castro and the destabilization of the government of Salvador Allende in Chile.

The administration's handling of covert action draws sharp criticism from some officials and former officials of U.S. intelligence agencies.

"I believe the excessive emphasis on covert action by the Reagan administration, especially covert action for objectives that are less than critical for our country, will jeopardize the CIA's ability to do covert actions that can be very important to our country in the future, " said former CIA Director Stansfield Turner.

The CIA did not respond, but one administration official noted that Turner fired about 800 covert agents during his tenure.

SHIFT UNDER REAGAN

It is not surprising that a shift from traditional diplomacy to secret action has occurred during the Reagan administration. Two key presidential advisers, CIA Director Casey and Oliver North, the deputy director of the NSC's Office of Political Development and Political-Military Affairs, have backgrounds that include extensive training in unconventional actions.

Casey, a veteran of the pre-CIA Office of Strategic Services, which conducted secret operations behind enemy lines in World War II, has rebuilt the spy agency's covert action division. It had been decimated under Turner, President Carter's CIA director.

North, a Marine lieutenant colonel who specialized in unconventional warfare, was a key player in the Iran affair and also oversaw a once-secret network to provide aid to the Nicaraguan rebels.

The NSC, with North in the lead, has conducted at least 10 of the Reagan administration's covert actions -- including the Iran project, which the president acknowledged Thursday night in a nationally televised speech.

Some of the once secret operations have been exposed and become famous, such as funding for the estimated 300,000 anti- Communist rebels in Afghanistan, Angola, Cambodia and Nicaragua, an effort generally known as the "Reagan Doctrine."

But many of the other programs, most still active, have remained largely secret.

They include, according to interviews with congressional and administration sources:

* Iran: Reagan's involvement with Iran dates to March 1981, when CIA briefers reportedly advised the House and Senate intelligence committees that the president had authorized a plan to aid Ayatollah Ruhollah Khomeini's opponents based in Turkey, Egypt and France.

While it is unclear whether the plan was implemented, Reagan said the flap over this year's arms shipments to Iran was not only a move to free the hostages, but also an effort to influence events in that country.

Arms shipments also have a precedent. In 1981 and 1982, Israeli officials were widely quoted as saying they had shipped American-made weapons and military spare parts to Iran with notification to Reagan.

Israeli officials also were quoted in 1982 as saying that one of the purposes of sending weapons was to bolster Khomeini opponents.

The latest Iran operation began 18 months ago to free the hostages held in Lebanon, end the 6-year-old Iran-Iraq war and persuade Tehran to curb its role in international terrorism, Reagan said.