APRIL 17 MARKS the 25th anniversary of the landing at the Bay of Pigs by CIA-supported Cuban exiles. It was a Monday in 1961, with an uncertain dawn and an ominous twilight.

The worst day of the operation was the following Wednesday. That was when those of us in the CIA's Cuban task force, headquartered in a former WAVE barracks near the Reflecting Pool, knew the landing was a failure beyond salvage. The invasion force had been routed.

The Cuban exile military commander of Brigade 2506 was about to abandon the fight. In what was to be his final radio report, his voice was clear. There was no static to muffle the obscenities he used to describe the American government. He cursed us as individuals.

The Cuban brigade commander had been a friend of the CIA's Washington task force chief; that man's face was white with remorse and fatigue as he listened to the transmission from the Cuban beach. The Marine colonel who had been seconded to the CIA from the Pentagon to direct the military aspects of the operation held his hand over his face, as though trying to hide. One officer scratched his wrists so viciously that blood stained his arm and darkened his fingernails. Another rushed from the room to vomit in a wastebasket.

The Cuban brigade commander radioed that he was standing in the shallows. "I have nothing to fight with . . . . Am heading for the swamp."

He cursed us again. Then it was over. The radio was dead.

To this day I am haunted by the image of that Cuban exile commander on the beach. It is my worst memory of abandoning an ally, but it isn't the only one. In my 25 years with the CIA, I was aware of too many instances in which allies and agents were left stranded after a successful operation or dumped after a failed one.

Paramilitary covert action has never been easy for the United States, even in what some intelligence professionals remember as the good old days. We have tended too often to leave our friends -- individuals and groups -- hanging out to dry in hostile circumstances. The reasons for this continuing difficulty tell us some painful things about our society: we are impatient and some-times hypocritical; our covert-action operations are too often tactical missions, short-term ventures for short-term ends. We ask people to take risks for us without fully comprehending the logiistical -- and moral -- commitments we have made to them.

The covert-action problem is worth taking seriously now, at a time when the U.S. is embarking on important new commitments to paramilitary forces around the world. Whatever one thinks of the merits of the various "freedom fighters," we should recognize that once our country makes a commitment to them, it is unfair, and perhaps immoral, to turn our backs.

The Bay of Pigs illustrates the difficulty we have had, even in the glory days of the CIA, in delivering on our commitments. The primary reason for the humiliation at the Bay of Pigs was President Kennedy's last-minute decision to cancel the sorties of Cuban exile aircraft, their engines warming up on Central American tarmacs, to provide air cover for the invasion force of 1,400 exiles and a platoon of tanks.

The young president -- in office less than three months -- manfully accepted responsibility for the fiasco. But there was sufficient blame to spread around, including CIA's reluctance to recognize that the amphibious landing might be beyond its capabilities and the agency's failure to make that clear to Kennedy. We were the professionals, and we were aware of the intelligence maxim that you can't cover a hippopotamus with a handkerchief. You certainly can't cover a tank on a Caribbean beach with one.

The realization that we had let our Cubans down was the most painful personal element of that disaster 25 years ago. Most of them were taken prisoner, some died. We had recruited them, indoctrinated and trained them, and sent them into battle without the air cover they expected ("The skies will be yours," we had promised.) We failed our contras. We didn't call the Cubans of Brigade 2506 that in 1961, but they were our contras.

CIA officers aren't sentimental. They understand that in espionage or counterespionage operations there are often personal casualties. But these victims know what they are getting into; they are spies who, for one motive or another, often money, have betrated their country. Most spies know they must be prepared for a day of reckoning if things go wrong. Thus professional American case officers who manage spies perform their assignments without having to fine tune their sense of personal ethics.

But even the most hardened intelligence officer is uneasy when foreigners supporting a CIA covert-action operation are the victims. These are people who volunteered their services or were persuaded to rally to a cause. When they are abandoned it is disquieting for their American case officers, who carry away a burden of remorse and second thoughts when they walk away from the wreckage.

It has happened too frequently. The CIA has recruited and trained foreigners for paramilitary or political action endeavors and, when the operations were concluded, left them out in the cold. Not because the CIA is institutionally callous. Generally, the problem has been that post-operation support has been beyond the agency's capability or authority -- such as funding a long-range aid program following a decisive change in leadership abroad.

There is a long list of these failed paramilitary ventures. I would be uncomfortable revealing details of those endeavors, and even if I were inclined to do so, the CIA's Publication Review Board would remind me of my secrecy oath. But the burgeoning public literature on U.S. secret operations contains several case histories.

In his memoirs, former Director of Central Intelligence William E. Colby describes the covert paramilitary support given by the CIA in 1972 to Kurdish mountain people fighting Iraq in a border dispute, support requested from Richard Nixon by the Shah of Iran. Three years later the Shah, having settled his own differences with Iraq, had no further interest in the Kurds. American support to the mountain fighters ended abruptly. "CIA's cable traffic," writes Colby, "suddenly was jammed with requests to help the refugee and exiled Kurds instead of shipping arms and military supplies to them clandestinely."

The most comprehensive study of the CIA is the Thomas Powers book, "The Man Who Kept the Secrets: Richard Helms and the CIA." While I cannot vouch from personal knowledge for his examples from Southeast Asia, he writes of three illustrative episodes:

The Sumatran rebel colonels: they were abandoned to their fates in 1958 when the CIA operations against Achmed Sukarno in Indonesia failed abruptly and embarrassingly, albeit in secret.

The Meo tribesmen who were a CIA army during the Vietnam war: In the beginning a few hundred of them were a small-unit guerrilla; later they became a 30,000-man army. In 1975, a "pitiful remnant" of 10,000 escaped to Thailand.

Nine teams of Montagnard tribesmen on an intelligence and harassment mission in North Vietnam: When President Johnson halted air strikes over North Vietnam in 1968, resupply drops to the Montagnards ceased as well. The CIA had to abandon them behind enemy lines. Some of the agents were taken prisoner, others perished.

Now the rules have changed. The secrecy that once prevailed, and hid details of the recruitment and abandonment of paramilitary forces, has given way to a system of quasi-public debate. Now even the planning for future operations is in the public domain, as we can see from the public debate about support to our contras in Nicaragua.

The contras debate has given the American public a glimpse of the people who actually do the fighting in paramilitary operations, and the reality isn't always attractive.

For example, it is difficult to detect much that can be called romantic or admirable about the individual contras in Nicarauga, and charisma has eluded their commanders as well. Even their war name is pathetic. Contra as a verb in Spanish means to be against; thus a contra is "an against". The CIA-supported dissidents who overthrew a leftist government in Guatemala in 1954 -- a political action achievement that President Eisenhower thought was dandy -- were dubbed "liberators". Others who have attacked their own governments in similar situations have been described as fighters or rebels for one cause or another, or, on a loftier level in Santo Domingo in 1965, as constitutionalists.

The national debate over support to the contras extends to the intelligence community. A survey of active duty officers and former intelligence professionals indicates the majority believe we should back the contras in Central America. Most of that majority take the position because of personal political conviction and implacable distrust of the Cubans and Soviets. A few believe that intervention in Central America is morally wrong. A larger segment of the minority of CIA professionals who oppose assistance to the contras fear that the fallout from covert action inevitably obscures and threatens CIA's primary business of gathering and processing intelligence.

All intelligence professionals agree on one aspect of modern covert action in Central America. If it is decided that we will cease supporting the Nicaraguan contras we should cut the ties sooner rather than later, combining to the extent possible a humane yet cauterizing method of disengagement. If we decide to keep the contras on our paramilitary tether, we should not jerk them in and out of the conflict in reaction to political whims or each political development. Deciding each 90 days if we will support them is an absurd evasion of responsibility. If we decide to keep the contras, they deserve to know where they stand with us. Now, after four years of U.S. support, the Nicaraguan contras in the field don't know where they will be next month, or next year.

In the past decade the rules of the covert action game have changed. From the viewpoint of the professional intelligence officer, the covert-action option -- what has been described as "the tool of middle resort" -- began to deterioriate in the wake of the sensational headlines and public scrutiny of intelligence operations in 1975. The capability for covert action operations remained, but the chances of keeping them secret diminished drastically.

Despite the transparent cover of modern U.S. covert-action operations, the Reagan administration has found it useful to take advantage of CIA's flexibility to originate and fund operations that for some are now identified as "overt covert action." Future administrations probably will, too.

The current overt-covert situation leads some people to question why the U.S. shouldn't drop the fig leaf. Our government shouldn't be ashamed to support democratic forces overseas, this argument runs, and therefore we should fund deserving military groups and political parties openly and directly. Although refreshingly straightforward, this approach overlooks one reality. In many cases the beneficiaries of such aid would be the first to insist that it be given discreetly. It would be political suicide for them to accept direct foreign assistance, just as it would be for a political party in this country to take money from abroad.

The intelligence professional deplores the developments of recent years, and yearns for the day when covert-action operations will no longer be conducted in Macy's window. The intelligence operative looks forward to the time when covert-action capabilities are not used as smoke-making machines, the bellows often being pumped by someone wishing to send a political signal rather than to achieve a clandestine objective. But the intelligence professional recognizes that paramilitary and political action operations in our society will be, without question, more overt than covert in the future.

If that's the way it is going to be, then the good soldiers at CIA will salute and obey their marching orders. That is one reason presidents will continue to use the Agency for covert operations when overt action might be more practical. (The CIA "good soldier" and "can do" tradition is, on balance, a useful attribute. Its negative side was evident during the planning for the Bay of Pigs: CIA should have ignored the tradition and confessed to Eisenhower and Kennedy that the amphibious operation, if conducted at all, should have been managed openly by the Pentagon and not a secret army.)

The opening of covert operations to public scrutiny has one benefit for the practicing intelligence officer. Now the moral responsibility toward those recruited to serve our ends in foreign covert operations has become a more general, public one. Ethical questions no longer must be resolved by a few people deliberating in the shadows. Instead, they are debated in public forums, or in private chambers from which leaks drip immediately. Guerrilla wars, and sometimes even the tactics the insurgents will employ, are now negotiated in a public forum, most recently by votes in Congress.

Now that Congress and the public are part of the dirty work, let a former case officer offer a word of caution: Every blueprint for covert action should include, as a routine matter, a disaster plan. This plan should set forth a course of action to be implemented when things go terribly awry. The Bay of Pigs project was a good example of the failure to prepare for disaster and, when it came, the inability to cope with defeat and minimize damage.

Today all of us must share responsibility for American foreign policy decisions that establish alliances with rebels abroad. Given the reality and complexity of the U.S.-Soviet conflict, each case is different and each decision is tricky. We should pause before reaching a personal conclusion, or before making our views known to our Congressional representatives. Because once we resolve as a government to support contras of any kind in any place, we have incurred a serious responsibility.

The personal decision to support a "covert-action operation" -- the quotation marks are now mandatory -- should be made only after serious introspection. But if when all the votes are in, our government recruits foreigners to fight for us, we should all resolve that we, as a nation won't abandon them if things go wrong. We must not give them a reason to curse us, or leave them with no option other than heading for a swamp.