IN LAST WEEK'S clashes around the globe, from the Gulf of Sidra to the jungles of Honduras, the United States was using a military strategy that goes by the name of "proportionate response." In simpler language, it is often known as "tit-for-tat." Libya shoots a missile at our planes? Our planes shoot a missile at their missile site. Nicaragua sends troops into Honduras? We helicopter Honduran troops in to attack the Nicaraguans.

The admirals and generals seemed to be fervently embracing the tit-for-tat strategy last week. This is odd because it is similar to the strategy they've been bitterly denouncing in the last dozen years of rehashing the lessons of Vietnam. It has the same pitfalls as "gradual escalation," "the eyedropper tactic," and "fighting with one hand tied behind our back" which called for the American military to fine-tune military power so some pressure was put on Ho Chi Minh, but not too much.

The tit-for-tat strategy gives the enemy the initiative because the American military must provoke someone like Qaddafi to punch so the well-prepared counterpunch can be delivered. But the widest, deepest pitfall of all under tit-for-tat is that it doesn't win anything decisively. There is no clear objective. The U.S. military is kept punching and dying to make diplomatic points. Unless political leaders can clearly explain why soldiers are punching and dying, the public -- and then the Congress -- gets turned off by the endeavor at hand and refuses to support it any longer. Then the military, which felt it was just following orders, is blamed for not knowing what it is doing. All this just happened in Southeast Asia.

So why, a little more than 12 years after the last American combat soldier left Vietnam, are U.S. military leaders walking smartly down the same road again -- as they did in Lebanon and are doing in Libya and Central America? The Joint Chiefs are going along with tit-for-tat once again without protest. There is some distant rumbling among their former colleagues now retired, like the respected Army general officer with impressive Vietnam credentials who told me: "If Nicaragua is as big a threat to us as President Reagan told us it is, we should either have the guts to go down there with troops and clean it out or shut up about it. What we're doing now is no strategy at all."

Yet the current embrace of tit-for-tat becomes less surprising the longer one stares through the American military's telescope and picks out these features on the landscape of 1986:

*A hardline Republican president named Ronald Reagan wants to look tough by "doing something" but is just as apprehensive as a moderate Democrat named Lyndon Johnson was about military operations which might cost American lives and inflict what the military calls "collateral damage" -- a euphemism for killing innocent women and children in the target area.

*The world is linked by television screens which any dictator with a camera can dominate for a night with pictures of "collateral damage" or of a captured American pilot or sailor apologizing, after torture, for his deeds. North Korea's Kim Il Sung (Pueblo crew), North Vietnam's Ho Chi Minh (downed fliers), Iran's Ayatollah Khomeini (U. S. embassy hostages), Syria's Hafez Assad (Lt. Bobby Goodman), Yasser Arafat and assorted hijackers all have shown they know how to use TV cameras to embarrass, inhibit and influence the United States.

*The American military is strictly volunteer, with no prospect that either Reagan or Congress will bring back the draft in peacetime to speed the deployment of replacements to a battle, should it become too big for volunteers to handle. Vietnam started out as a brushfire war, but the Army had 1,570,000 men and women in uniform at its height in 1968. Today's Army is half that size at 781,000. Washington Post correspondent Bob Woodward has reported that the Pentagon warned Reagan administration officials exploring the possibility that it would take up to six divisions -- more than 90,000 troops -- to overthrown Qaddafi in concert with Egyptian forces. The All-Volunteer Force could not take on that big an effort without leaving other trouble spots all around the world dangerously uncovered. The tit-for-tat strategy does not require this kind of manpower.

*The American public would almost certainly desert, condemn and vilify everything military -- just as it did when Vietnam went sour -- if their sons started dying in places of no visible consequence to the United States like Libya, Nicaragua and Lebanon. The Vietnam trauma has generated a "never again" school within the military when it comes to getting too far out ahead of public opinion. A Washington Post-ABC public-opinion poll released last week indicated that 62 percent of the American people oppose their government trying to overthrow the government of Nicaragua.

*A new generation of "smart" weapons allows tit-for-tat to be implemented with little risk of starting a big war, getting Americans killed or captured, or causing the dreaded collateral damage. One family of such weapons is even called "fire and forget." Punch off the missile and then run. The missile will find its own way to target. No bayonet needed.

Smart weapons promise to solve so many problems they have become irresistible, as evidenced by their extensive use against Libya last week. U.S. Navy A6 bombers launched Harpoon cruise missiles with 500 pound warheads at Libyan patrol boats from miles away, out of sight of the human eye. It was the computerized brain of the missile itself that locked onto the boat and directed the weapon to its target.

Navy planes fired Harm missiles into Libyan radars from a safe standoff distance. The missiles rode the Libyan radar beams right into the emitting dish and then blew up. If Russians had been at the nearby trailer at Surt, as expected, they would not have been killed by collateral damage. Meanwhile, if the U.S. pilots had been shot down, they would have landed in the water. With a little luck, U.S. helicopters, not Qaddafi, would have rescued them.

Smart weapons also promise non-involvement at the time Congress is demanding non-involvement -- at least that which is visible or direct -- by the American military in places that look like Vietnam. Nicaragua is the current case in point.

Take a smart weapon like the Stinger antiaircraft missile. It is shoulder-fired and directs itself to the target by seeking heat. The Stinger can be described as a tit-for-tat weapon because it can be sent to the contras as a response to the Soviets sending the Sandanistas helicopter gunships. It also could be described as a graduated response, not a sharp escalation by the United States. The American military would not be directly involved; it would keep its distance from the missile vs. helicopter battle, which could be bloody. As a result, this smart weapon matches all the requirements the generals and admirals could have for projecting American military power.

This look through the U. S. military's telescope shows the apparent advantages of the tit-for-tat strategy. What it does not show is that tit-for-tat has the same fatal flaw in 1986 in Libya, Nicaragua and Lebanon as it had in Vietnam. The strategy is a pacifier for frustrated presidents, demanding right wingers and restless admirals and generals. But nobody knows where today's tit-for-tat strategy is supposed to end up -- so it may bring nothing but trouble and divisiveness. Once again, as in Vietnam, there is no clear, agreed-upon objective. I hear echoes of former Secretary of State Dean Rusk saying that we are going to keep up what we're doing until they stop what they're doing. Whatever that meant.

A lot of people feel good about the United States finally punching Qaddafi in the nose. Hooray for our side. He deserved it. But what was the real object of the exercise? "If we have to have three carriers to go into the Gulf of Sidra to challenge a pissant country like Libya," a Navy pilot familiar with the exercise told me, "we ought to hang it up."

Why an armada? One carrier would have been plenty, two extra insurance, if navigating in those waters up to 12 miles from shore was the idea, as was advertised.

Was the real objective to bomb Libya heavily in hopes of leading to the overthrow of Qaddafi? If so, U. S. military leaders were carrying out a strategy which had an objective many of them opposed. Many military leaders would rather have a stable Libya with Qaddafi than an unstable Libya without him. Thoughtful military leaders warn against doing anything that destabilizes fragile Third World countries like Libya.

Was the goal of the naval exercise code named Prairie Fire to deter Qaddafi from terrorist acts? Again, administration officials deny this was the objective. Weinberger said last week he did not know whether crossing Qaddafi's "line of death" in the Gulf of Sidra would deter or incite the volatile Libyan leader. "I can't see how it would encourage him to do anything. Whether it deterred him or not requires the resident psychiatrist to come in and help us, and that is with his rationality. I just don't know." As Weinberger spoke those words in the Pentagon studio extra guards were on duty in the offices of top Navy officials in the building. The theory apparently was that Qaddafi would follow our strategy of tit-for-tat: Our Navy hit him; he would hit our Navy. But if Qaddafi ignores that script and sends a terrorist to blow up the Woodward & Lothrop department store, as terrorists blew up Harrods in London, to score his tat, what then? Is there a strategy? Weinberger's "I just don't know" answer is not reassuring here.

On the other side of the world, in Central America, the tit-for-tat strategy was taking us down another dark road last week. An uncertain number of Nicaraguan troops crossed into Honduras to attack base camps of the contras. The United States responded by flying Honduran troops near the battle zone but not into it. It was another version of tit-for-tat. Manugua sent troops into Honduras. Washington carried Honduran troops to fight them. And the Americans kept their distance from the fray so there would be no captives for the Sadinistas to display; no direct involvement to upset the Congress. The helicopter, in that sense, was another version of a standoff weapon for waging war in a half-pregnant fashion in the twilight zone of Central America.

But where is this strategy leading, if not on up a ladder of escalation with no objective at the top? Despite the Vietnam parallels, the Joint Chiefs of Staff are going along with tit-for-tat, probably because they cannot think of anything better to do given today's political environment.

The only place where the tit-for-tat strategy has had time to play out under Reagan is Lebanon. The results were disastrous -- but somehow forgotten. I watched from a front seat the strategy implemented heroically by the men ordered to carry it out. I was on the aircraft carrier USS John F. Kennedy for the full seven months of her 1983-1984 deployment, with most of that time spent off Lebanon.

A lone terrorist while I was aboard the carrier penetrated the Marine compound in Beirut on Oct. 23, 1983, and detonated explosives which killed him and 241 servicemen, mostly Marines. Reagan had sent the Marines into Lebanon with no clear objective. They were to provide a "presence." He vowed to avenge their deaths. Navy officers on the Kennedy, USS Eisenhower and USS Independence standing off Lebanon planned a retaliatory bombing strike. It was never launched.

On Dec. 3, 1983, two of the Kennedy's F14 reconnaissance planes were shot at by missiles over Lebanon. It was not the first time this had happened, but the Joint Chiefs of Staff recommended responding in kind by the next morning. They could have suggested using the battleship New Jersey standing off Lebanon. This would have provided the distancing and assured no fliers would be killed or captured . But, the chiefs told me afterward, they felt it would be more in keeping with the tit-for-tat strategy to employ carrier planes. They would be attacking the same kind of missile sites that had attacked them. Reagan approved the bombing raid.

The anti-aircraft sites selected for bombing were so small that the fliers had to dive low to see them clearly enough to -- as ordered -- avoid collateral damage. Low altitude increased their vulnerability and two bombers were shot down by soldiers firing "smart" shoulder-fired SA7 antiaircraft weapons. One pilot, Lt. Mark Lange of the Kennedy, was killed in the raid. Lt. Bobby Goodman, Lange's bombardier, was captured. Syria flashed Goodman's picture around the world to score propaganda points and eventually released him.

The Marines were withdrawn from Lebanon on Feb. 7, 1984. There had never been an objective, and none was reached. Tit-for-tat did not lead anywhere in Lebanon. The important question now is where is it taking us in Libya and Central America?