Finding a response to terrorism. With the return of hijackings to the headlines, US policymakers are pondering how to respond to the fresh challenges of terrorism. Some call for swift military response; others say it should be avoided. Several nonmilitary approaches, such as improved intelligence, have also been recommended to help avert terrorist attacks.

LAST October's hijacking of the Italian cruise liner Achille Lauro was, for many Americans, the last straw. Four months earlier, the agonizing hijacking of TWA Flight 847 to Tehran had left two Americans dead -- and the terrorists free. Frustration was mounting: The largest nation in the free world again seemed to be at the mercy of tiny bands of violent men and women.

So when United States officials announced that F-14 Tomcats had intercepted an EgyptAir Boeing 737 carrying the Achille Lauro hijackers and forced it to land in in Sicily, the headlines sang of success. The nation was jubilant: America, it seemed, had gotten tough, and the terrorists had been taught a lesson.

Within two months, another hijacking ended in a ``get tough'' approach -- involving, ironically, the identical EgyptAir 737, hijacked en route from Athens to Cairo and forced to land in Malta. But this time, after Egyptian commandos stormed the plane in an effort to free the hostages, 60 people were left dead. This time there was no jubilation.

How can the world best respond to international terrorism?

In the past year, that question has assumed new prominence -- in part because terrorism, under several accepted definitions, is on the increase (see chart).

This year, too, the UN has finally come together on the subject in three landmark resolutions, all unanimous, condemning terrorism ``in all its forms'' -- hostage-taking in particular.

Yet as the debate over terrorism has become increasingly vocal -- carried on through newspaper columns, in full-page advertisements, and in such television specials as this month's NBC program ``Under Siege'' -- it has also narrowed in focus. The recent maneuvers of the US Sixth Fleet off the coast of Libya only serve to clarify the importance of what has now become a widely discussed question: What is the role of military force in combating international terrorism? Role of military force debated

On one side are those who argue for swift military action against terrorists. They see firm retaliatory or preemptive measures as the only way to signal US resolve.

On the other side are those who argue that military force is almost always an inappropriate response -- if only because the target is so elusive. Terrorism, they argue, must be fought through diplomatic and legal means, since retaliation simply fuels more terrorism.

Both sides agree, however, on one thing: In the past year, US attitudes toward terrorism have hardened.

``We find a lot more support for vigorous action than there was before,'' says Robert Oakley, director of the State Department's Office of Counter-Terrorism and Emergency Planning. ``I think that the administration can go a lot farther in the use of force than it could have gone a year ago without risking a political backlash.''

What's behind this trend?

While rising frustration is certainly part of the reason, other long-term patterns are also at work. Half a generation after Vietnam, the nation's repugnance toward the military has lessened. Patriotism is on the rise. Defense spending is up. Military enlistments have been growing.

And popular culture -- including Rambo movies, week-night television shows, and war toys and their related cartoons sold in unprecedented numbers to the nation's young -- increasingly portrays a ``macho'' America defending itself by firepower against external threats.

Some students of terrorism even trace the beginning of the shift to a particular day: Oct. 23, 1983, when a truck-bomb exploded at the Marine barrack at Beirut International Airport, killing 241 US servicemen.

Two days later, Secretary of State George Shultz, using unprecedentedly strong terms, told a New York audience that ``we cannot allow [the US] to become the Hamlet of nations, worrying endlessly over whether and how to respond.'' US responses, he noted, should ``go beyond passive defense to consider means of active prevention, preemption, and retaliation. Our goal must be to prevent and deter future terrorist acts.''

His remarks stirred considerable debate -- focused most succinctly by Defense Secretary Caspar Weinberger, who expressed grave reservations about the use of military force unless there were, in his words, ``clearly defined political and military objectives.''

``The popular perception of combating terrorism,'' says Noel Koch, who oversees the Defense Department's counter-terrorism efforts, ``is that you rock 'em and sock 'em and put 'em into a box.''

``It doesn't work that way,'' he adds, noting that ``you're not going to stop terrorism in one fell swoop.'' If you try to do so, he says, the probable result is ``you will be perceived as a bully.'' How to define terrorism

At bottom, the real question being debated concerns the very nature of terrorism itself. Is terrorism best thought of as crime -- the traditional way of viewing it?

Or does it need to be seen as a form of low-intensity warfare, whereby such state sponsors as Libya, Syria, Iran, Cuba, and the Soviet Union (and even, some would add, US actions -- toward Nicaragua, for instance) use warfare ``on the cheap'' to destabilize enemy nations?

How America answers these questions will largely shape its counter-terrorism policy. If terrorism is a crime, it needs to be fought within the tight limits of legal systems, with punishment only following proof of guilt.

If it is warfare, however, a range of military options opens up -- including, in some cases, the abrogation of normal civil rights, especially for the accused.

Ray Cline of Georgetown University's Center for Stategic and International Studies explains much of today's terrorism in the context of ``a basic systemic conflict in international affairs between the Soviet Union and the United States.''

Noting that neither side appears willing to resolve smaller conflicts through a nuclear exchange or a conventional war that could escalate into nuclear war, he argues that state-supported terrorism is now being used to achieve some of the same effects as larger-scale warfare in destabilizing the enemy.

But Oliver ``Buck'' Revell, assistant director of the Federal Bureau of Investigation, who oversees what most observers praise as a highly effective antiterrorism operation within US borders, sees it strictly as crime. ``If you classify it as war,'' he says, ``then you give terrorists a standing that they don't deserve.''

Mr. Koch agrees. ``It's crime,'' he says bluntly, ``very simple, down-and-dirty crime of varying levels and degrees of sophistication. And you have to deal with it that way.''

Rand Corporation consultant Paul Henze takes a different view. ``If you think of it as crime,'' he says, ``you must have absolute proof, and if you make any procedural errors you must drop the case.'' To do that, says Mr. Henze, gives the sponsors of terrorism ``an opportunity to get their people off scot-free every time, because the whole operation will be designed to lead to the circumstances that will cause it not to be prosecuted or not to be dealt with.'' Beyond military action

However this debate is resolved, most observers recognize that a fully developed counter-terrorism strategy must have a number of facets beyond military action.

In an effort to clarify US strategy, a commission headed by Vice-President George Bush, formed last summer shortly after the hijacking of TWA 847, has already handed its findings to the President and is scheduled to report publicly later this month. Among the issues it is expected to discuss are:

Improvements in intelligence. Penetrating terrorist groups not only helps thwart incidents and save lives, but also causes terrorists themselves to become increasingly suspicious of one another. Given the potential for terrorist incidents using chemical, biological, or nuclear weapons, there is growing agreement that more ``human intelligence'' capacity is needed.

Better physical security. Mr. Shultz is asking for $4.4 billion to rebuild and ``harden'' US facilities around the world -- a request that has already run head-on into the Gramm-Rudman budget cutbacks. Better security has already reduced the number of hijackings and incidents directed against diplomats -- and caused terrorists to turn toward ``softer'' targets, such as American businessmen. But the business community is also spending billions of dollars hardening itself. The result could be a shift to the even softer targets of tourists -- a shift which may be reflected in the Rome and Vienna airport incidents and in a spate of bombings in Paris earlier this month. State Department officials estimate that terrorism cost the countries around the Mediterranean about $1 billion in lost tourism bookings in 1985 and expect the figure to rise even higher in 1986.

The role of the news media. Most observers warn against any move toward censorship -- although some look favorably at such things as a British law governing kidnapping, under which editors are kept informed but are not free to publish until the situation is resolved. With amateur video cameras increasingly available, however, terrorists can film their own news: Last January, terrorists thought to be in Lebanon released a 56-second videotape of kidnapped US diplomat William Buckley, excerpts of which were broadcast by NBC during the evening news.

Cutting support for terrorists. Few terrorists today work alone. Many have international links to other groups, and a considerable number receive assistance from various nations in the form of funds, training, protection in embassies and safe houses, false documents, and use of diplomatic pouches to ship arms. Counter-terrorism options include the use of economic sanctions against the offending nations and landing rights restrictions on their national airlines.

Improved international cooperation. Extradition treaties governing terrorists, better coordination among intelligence agencies, and agreements to take a united stand against terrorism are under discussion.

More careful attention to US foreign policy matters. Critics of US policy -- especially as it relates to the Middle East, North Africa, Latin America, and other areas where terrorism is prominent -- contend that unwise policies provoke violent anti-American responses. Some critics, for instance, blame the death of the Marines in Beirut as much on what they see as mistaken policy decisions as on inadequate security.

On one point, however, there is widespread agreement: The nation cannot afford to surrender its fundamental moral and democratic principles in the battle against terrorism.

Summarizing his feelings, former Central Intelligence Agency director Stansfield Turner (who is currently writing a book on terrorism and democracy) notes that ``I just believe fervently that we've got to be careful that in the name of defeating terrorism we don't become terrorists.''