The House Intelligence Committee tried hard last week to get a grip on covert U.S. paramilitary operations such as those in Nicaragua and learned that the only way it may be able to curb the CIA is the way Congress curbs the rest of the executive branch: holding on to the purse strings.

But the prospect of any real control is heady stuff.

Rep. Wyche Fowler Jr. (D-Ga.) summoned some of America's most knowledgeable former spies and spy watchers to conduct a rare public debate about intelligence legislation, specifically his proposal to require prior congressional approval of any CIA military or paramilitary operations. Money would be doled out in small chunks as the committee approved of the way things were going.

In the intelligence world, this is revolutionary talk. At present, the intelligence committees are informed "in a timely fashion"--in practice, within 24 hours--of the start of covert operations, and committee members have the right to object. They frequently do.

But the CIA does not have to listen. It has a huge, secret "contingency reserve fund." The intelligence committees clear it in advance and in total every fiscal year as part of the intelligence authorization act. The agency uses that fund to keep operations going, and growing, when the White House wants them to, no matter what intelligence committee members think.

"It happens all the time," Fowler said. "That's what these hearings are all about." There are "a couple of other parts of the world" where worrisome things are going on now, he said.

Even witnesses who deplored the Nicaragua operation where CIA-backed rebels are harassing the leftist government said the president must retain the right to launch such projects as part of his constitutional mandate to conduct foreign policy.

The intelligence committee can try to cut off funds for a particular program after the fact, as it has in the Nicaragua case, and should do so when it feels strongly, the witnesses said. But this approach is "just so messy," Fowler complained.

For example, the House agreed, 228 to 195, to stop the Nicaraguan rebels, but the Senate must concur before the money dries up. The Senate Intelligence Committee voted last week to provide $19 million more for the Nicaragua operation. Clandestine work in Angola ended with the Clark Amendment in 1976 only after enormous public outcry.

"Once an operation starts, it's almost impossible to stop. The ground changes," Fowler said. As the program begins to have some impact, it inevitably becomes public. Backers then argue that people have committed their lives and need increased U.S. aid to avoid a retaliatory bloodbath.

"The word and the prestige of the United States is on the line . . . . It's a totally different scenario," Fowler said.

In fact, covert paramilitary operations "are the methods by which the United States gets dragged into military conflict," said Morton H. Halperin, director of the Center for Strategic and International Studies.

Five wars in U.S. history have been declared, Vietnam and Korea not among them. Various secret studies have found "few, if any, cases where covert paramilitary operations have been effective" in achieving their original goals, said David Aaron, former deputy assistant to the president for national security affairs.

The committee considered the idea that paramilitary projects therefore come under the Congress' constitutional power to declare war.

"If Congress is prepared to make a declaration of war on Nicaragua, I personally would support it," said Ray Cline, former deputy director for intelligence at the CIA. But since that is "not likely," he added, a "less forthright" approach has been used.

In effect, he said, paramilitary and military operations have replaced war as the 19th-century Prussian military historian and theorist Karl von Clausewitz defind it: "diplomacy by other means."

The committee also considered the line between making foreign policy, in which Congress has an official hand, and its execution, in which it has no formal role. Sending surrogates to make secret war for U.S. causes is clearly making policy, Chairman Edward P. Boland (D-Mass.) said, "but the only time we get in on that policy is in providing the tools and financing to implement it."

Sometimes policy forged publicly between Congress and the White House is directly opposite to the aim of covert action, Rep. Norman Y. Mineta (D-Calif.) said, and "it makes me feel like the proverbial mushroom," being kept in the dark and fed horse manure.

Halperin recalled that under Lyndon B. Johnson he helped write official declarations that proof of U.S. willingness to live in peace with China during its cultural revolution chaos was that the United States was doing nothing to foment it. He then learned that the CIA had a massive covert program of internal disruption in China.

Further, he said, the program required that China be painted as expansionist and liable to invade Vietnam, even as the CIA's own analysts, as ignorant as any outsiders about the covert program, were reporting that China was inward-looking and sought only domestic stability.

Similarly, Aaron said, the problem in Nicaragua is "covert U.S. policy, not covert action."

But former CIA director William J. Colby said that is inevitable. Realpolitik often demands a friendly facade towards a country, he said, while "underneath we are aware that we must do something to change the course of that government."

After three days of such testimony, Fowler's proposal appeared moribund. Most of the Democrats seemed convinced that foreign policy requires what one member called "wriggle room," presidential authority to learn secrets, spend secret money and take secret action to advance U.S. goals without prior congressional clearance.

But everyone also agreed that Congress has a clear right to restrict the CIA's wriggle allowance. It could still require that the agency justify its spending plans before it gets big chunks of money.

One of the three bills in Fowler's proposal includes a limit of $2 million in appropriations from the CIA's contingency reserve fund without approval from the intelligence committees.

Fowler is confident that the measure's wording exempts it from the Supreme Court's ban on after-the-fact legislative veto provisions. Most witnesses endorsed the concept of attaching strings at the time the fund is appropriated, although they said that this could be done without further legislation.

The possibility remains that, messy as it is, the current process works just fine for Congress in providing what the intelligence world calls "deniability" when foreign efforts go awry.

Real authority over covert action could make it even harder for Congress to reverse gears on its own policy. "Many in Congress don't want it to have that authority," Rep. Bob Stump (R-Ariz.) said.

Morton H. Halperin was identified incorrectly yesterday. He is director of the Center for National Security Studies.