Your reaction to the U.S. military action in the Gulf of Sidra depends a good deal on your assessment of the problem the Reagan administration intended to address.

If you believe that President Reagan's concern was the need to establish the right to free passage in international waters that Libya claims as its own, then the naval exercises off the Libyan coast and the response to the missile attacks those exercises provoked will seem reasonable. (Even so, you might find yourself thinking that a multinational diplomatic solution to the problem would have been preferable.)

If you believe that Reagan's principal concern was to sock it to Col. Muammar Qaddafi, the Middle East bully and protector of terrorists, then you might see the military maneuvers as calculated to goad the Libyan leader into suicidal rashness -- in other words, as deliberate provocation.

The announced concern is the first one. Qaddafi has drawn a "line of death" over the mouth of the Gulf of Sidra, as far as 120 miles from the Libyan coast, claiming it as Libyan territory. The United States and much of the rest of the world recognize only a 12-mile limit.

What makes this explanation somewhat less than convincing is that the naval operations began not in response to a territorial dispute but in the wake of charges that Qaddafi was harboring Abu Nidal, the terrorist believed to have masterminded last January's airport massacres in Rome and Vienna.

That was the beginning of the Reagan administration's effort to enlist international cooperation in isolating the "flaky" Qaddafi. But Reagan has been looking for an excuse to do a number on the infuriating colonel at least since 1981, when the word leaked out that Qaddafi had dispatched a hit squad to assassinate the president and other high U.S. officials. No hard evidence of such a plot was ever made public.

The suspicion, then, is that it was less a question of free passage than an excuse to zap Qaddafi that produced this week's confrontation, though it might well be that not even Reagan himself is sure which was the stronger motive.

For some U.S. leaders, it doesn't matter. Sen. Richard Lugar (R-Ind.), chairman of the Senate Foreign Relations Committee, believes both motives were operating and that either would have been sufficient justification for what took place this week. So does Sen. Alan Cranston of California, the assistant Democratic leader, who saw it as "planned as an action that might cause (Qaddafi) to act against us and then we could strike against a base of terrorism."

Maybe. But the Libyan humiliation seems more likely to trigger terrorism than to cure it. Up to now, international terrorism has been aimed principally at the situation in the Middle East, involving the United States primarily in its role as supporter and defender of Israel. The action of Monday and Tuesday now provides a motive for terrorism against the United States directly. Given the openness of this country and the suicidal attitudes of many of the terrorists, it may be impossible to prevent it.

In short, whether the U.S. motivation was freedom of international seaways or freedom from international terrorism, it is far from clear that the means the Reagan administration has chosen fits its purpose.

Of course, Libya was foolish to launch a missile attack against the powerful U.S. Sixth Fleet, and once that attack was launched, it seems perfectly reasonable that the Navy should strike back. But the suspicion is that, our injured innocence notwithstanding, we counted on just such foolishness.

It's one thing to be vigilant against the neighbor's nasty dog, quite another to walk back and forth in front of the neighbor's house with a string of frankfurters hanging out of your pocket and making noises like a cat.