A tense scene after the Marines were bombed in Beirut last year illustrates why the Joint Chiefs of Staff will approach with caution the question of launching a retaliatory strike against the terrorist group whose members murdered two Americans after hijacking a Kuwaiti airliner to Iran last week.

Marine Commandant P.X. Kelley was grieved and angered by the terrorist bombing at the Beirut International Airport on Oct. 23, 1983, which killed 241 U.S. servicemen, mostly Marines. But as he and the other members of the joint chiefs, the nation's highest military body, went over a proposed retaliatory strike, Kelley asked the burning question:

Will exposed Americans, including other Marines, be in more or less peril after the bombing of the targeted terrorist center in Lebanon?

The intelligence community could not assure Kelley that a retaliatory strike would have a deterrent value, making his Marines more secure.

His embassy guards in Beirut, as well as other Marines in Lebanon, were often vulnerable to terrorist rifles, grenades, mortars and bombs. Kelley concluded that the risks to his men outweighed the gains from retaliatory action.

President Reagan apparently agreed. The retaliatory bombing raid was planned in detail but was not executed.

The same question -- what will we get back? -- will be asked in any current or future U.S. government deliberations about retaliation for terrorist acts such as the hijacking of the Kuwaiti airliner. State Department officials believe that the four Moslems who hijacked the plane are members of a radical Shiite group based in Lebanon and linked to the Iranian leader, Ayatollah Ruhollah Khomeini.

At the same time that the Joint Chiefs of Staff and Defense Secretary Caspar W. Weinberger have been approaching retaliatory action with caution, Secretary of State George P. Shultz has been out front making a case for preemptive and retaliatory strikes, saying as recently as Sunday that "a great power . . . must bear responsibility for the consequences of its inaction as well as for the consequences of its action."

Whatever their reservations, the joint chiefs and the military officers in the trouble zones must plan retaliatory strikes in case the president orders one in a hurry. The Navy has been in this posture on its aircraft carriers in the Mediterranean, including making extensive preparations on the USS Eisenhower last month for a bombing strike against a terrorist complex in Lebanon.

In addition to worrying about what the terrorists would do in response to a retaliatory strike against them, military leaders planning preemptive and retaliatory raids must answer a long list of hard questions that have not been addressed in the civilian debates:

How can the terrorists be identified and their centers found, targeted and struck without killing innocent civilians?

Where should the strike be launched from? Given the lack of U.S. bases in the hottest terrorist regions, the Persian Gulf and the Middle East, aircraft carriers get the role by default.

How can the launching platform -- the carrier -- be protected from terrorists responding to an attack with suicide runs in everything from light planes to remote-controlled speedboats? U.S. intelligence officials believe two flight schools in Iran are training pilots on how to bomb U.S. ships with innocent-looking light planes such as Beech Bonanzas. One school is near Tehran, the other near the Strait of Hormuz. Pilots are being trained in both the Bonanzas and military trainers, according to Pentagon officials, in a program involving about 300 instructors and technicians.

What happens if U.S. servicemen attacking terrorist centers are wounded, captured or shot down? How could they be rescued? Where should air crews be told to go if forced down in an Arab country? Can safe houses be established? Can friendly natives be found in Moslem countries to help American military men on antiterrorist missions escape the terrorists?

Should servicemen sent on such raids be told to try to live up to the Code of Conduct if captured, despite the likelihood of torture, or are new guidelines needed?

These questions do not mean that the military would balk at orders to carry out a preemptive or retaliatory strike against terrorists. But military leaders who have confronted the hard realities of executing such strikes see antiterrorism as a new twilight zone.