If the Reagan administration didn't have a Gulf of Sidra, it would have to invent it. More so than any administration in memory, it requires some place to work out its frustrations over foreign-policy problems it is unwilling or unable to deal with in any definitive way.

The Gulf of Sidra, what's more, has the particular advantage of being reusable. This is, after all, the second time in six years that the Reagan administration, while testing Col. Qaddafi's territorial claims, has slapped down the predictably pitiful Libyan response and claimed a famous victory.

That first Sidra skirmish in 1981, when two attacking Libyan jets were shot down, is worth recalling as we assess the likely consequences of the latest effort to put Qaddafi "back in his box." That's the way White House spokesman Larry Speakes explained the point of the exercise.

Hailing the results of the 1981 incident, President Reagan cried out: "Let friend and foe alike know that America has the muscle to back up its words." His secretary of the Navy falsely boasted that the Reagan administration had done what the Carter administration dared not do. In the Carter years, the U.S. Navy made the same point of challenging Libya's outlandish claims to territorial rights over the Gulf of Sidra.

But there was a crucial difference. The Carter administration never pretended to be doing anything other than upholding the right of innocent passage in the open seas. The Reagan administration has made it clear that its real interest is not so much territorial rights as the deterrence of terrorism. Preparations for the massing of one of the mightiest American armadas ever assembled in the Mediterranean began in direct response to the Libyan connection to terrorist attacks on Israeli airline check-in counters at the Rome and Vienna airports last December, and to the earlier installation of Soviet SA5 anti-aircraft missiles in Libya.

The naval exercise, then, must be seen as a contrivance -- a way of giving Qaddafi a bloody nose for lack of any effective way of bringing force to bear directly against Qaddafi's increasingly vicious terrorist activities around the world.

It may have had a message for Moscow, as well, and one can only speculate on the implications for U.S.-Soviet relations. We have more to go on, however, when the question is put as it was by an anonymous official quoted by CBS: "What will Qaddafi do now to preserve his manhood?" That the question would even be put that way by a responsible administration official suggests a mindless misreading of the problem.

The record itself does not encourage the notion that Qaddafi is much cowed when his feeble forces are zapped by a mighty American armada. Since the 1981 incident, he has made himself more and more of a menace to international law and order. There is no reason to believe that his latest humiliation at the hands of the U.S. Navy will be any more inhibiting this time around.

American audiences may swell with pride in the way that U.S. muscle has been successfully flexed. Many will share the view expressed by Senate Foreign Relations Committee chairman Richard Lugar (R-Ind.) that Qaddafi has been "proven to be so impotent."

That's a logical analysis by American standards: Qaddafi "lost," didn't he? Not in any sense that matters to him, is the answer I get from the Arab diplomats and from American experts on the part of the world that matters to Qaddafi. However he may now respond -- by instigating terrorist acts against Americans in Europe, wherever -- it will not be to "preserve his manhood." He is already David against the American Goliath, playing to an Arab public opinion that doesn't expect David to win and looks upon suicide missions as heroic.

Some authorities expect a rash of terrorism unrelated to any string-pulling by Qaddafi. Experts estimate there may be as many as two- dozen terrorist organizations responsible to no single mastermind, but easily inflamed by almost any display of "Western imperialism" -- or the slightest sign of indifference to it. Hence the hasty efforts of the so-called moderate Arabs to express their disapproval and the protests from at least two NATO allies, Greece and Italy, who provide facilities for U.S. naval forces in the Mediterranean.

Ironically, the most persuasive criticism of the administration's policy comes from Arab diplomats and American experts who would like nothing better than to see Qaddafi brought down, but believe that the administration's approach is not only building Qaddafi up but undermining U.S. influence in the area. They would favor quieter, covert efforts to encourage international opposition in Libya. But the Reagan administration strategy, they insist, has just the opposite effect. As America's Public Enemy No. 1, Qaddafi stands taller at home and in the eyes of extremist elements throughout the Arab world.

It is entirely proper for the United States to assert, regularly, the right to freedom of navigation, at some risk of provoking an attack. But it makes no sense to do so with the deliberate intention of providing a pretext for an ineffectual punishment that doesn't fit the real crime you have in mind.