As Americans were preparing to send Marines ashore in Lebanon, Defense Secretary Weinberger agreed to answer some of the questions that have been raised about their mission and about the deployment of American forces in general. We talked with him on Thursday.

Q: The other morning you said about the new American peace-keeping force in Lebanon that if, apart from isolated incidents, someone started to shoot at them, they would be withdrawn. If Jimmy Carter had said that, he would have been lynched. What does that mean?

A: I don't think it's a peace-keeping force, it's a force which has a very special mission. The previous force had a special limited mission also -- to get the PLO out without incident, to help to make sure that when they disengaged from close combat position, something roughly the equivalent of a rear guard was provided so that they could get out -- and they did -- without incident. That task was finished and that force withdrew.

This force is going in again by the president's specific direction, not on a combat mission, to help the new Lebanese government that has just taken office. They will go in to help them reassert their sovereignty.

We want to have the Israeli forces completely out of Beirut before they go in. We want the process that had begun under Bashir Gemayel, to integrate all the private armies and militias. His brother, we understand, intends to continue that. During that process it's essential that Beirut be left basically undisturbed and that the Lebanese armed forces that move in and take over the positions have the knowledge that they have a force that can interpose itself between them and anyone else during that period. There are still far too many foreign forces in Lebanon -- Syrians, Israelis and perhaps some Palestinian Liberation people up in the north -- and it is essential to have that interposition force as a deterrent to any adverse actions against the new Lebanese government.

Q: When you use words like "interposition" or "deterrent," or send military there for whatever particular mission, the idea of their being military is what gives them their influence, their power, their force. If they are to be so severely circumscribed in what they can do, doesn't that undermine the force they project? Shouldn't we have 800 foreign service officers instead. What is it that these Marines bring that should influence people in Lebanon?

A: Well, the fact that they are there, and that they are trained and that they have a mission that they carried out very successfully last time under very similar circumstances. They went in then, they had ammunition, they had light arms, they had organization, they had behind them the fleet, and they had all of their inherent capabilities. So did the French and the Italians. That provided a sufficient deterrent to any attempts to interfere with the departure of the PLO, which was their mission. Not a shot had to be fired.

Q: Suppose the multinational force were to witness some terrible bloodletting. What would be the authority or the orders of those fellows?

A: They will have rules of engagement that will try to cover as many contingencies as possible. Most of them relate to their own self-defense and maintaining the conditions necessary for them to complete their mission, which is to interpose themselves and let the Lebanese government take over Beirut. Commanders in the field have to have a large amount of discretion under emergency conditions.

Q: We are a little bit schizoid in this country right now. On the one hand, we talk about the need for greater defense, for a bigger budget, for doing a lot of things. We talk about threats and dangers. At the same time, if there is ever a man in uniform sent anywhere we become traumatized -- if there's a picture of a fellow in El Salvador who was supposed to be an adviser and he's got a gun. There is great agitation on the Hill about got a gun. There is great agitation on -- the Hill about these Marines. What does this say to you?

A: What it really says to me is that we have the same value for human life that we've always had. That we have the same reluctance to have any of our men in uniform injured or killed. I think that's a pretty healthy thing. The strength that we have to have is a totally different thing. We have to have the ability to have a force that can go in on two days' notice in the Mediterranean and be protected by carrier battle groups and all the rest. We have to have that. That gives us the ability to maintain peace for ourselves and our allies and we've been instrumental in that process for a couple of generations now and we'll continue to be.

But we are very worried about any loss of human life. We recognize that it's inevitable in some situations, as the men who enlist voluntarily in the services recognize that it's inevitable. But you don't court it and you certainly do everything you can to avoid it. The military exists only for one purpose and that's to carry out the foreign policy of the president. The foreign policy of the president is to return peace to Lebanon as quickly as possible, and the way we believe that can best be accomplished, with the least involvement of human life, because there's been far too much loss already, is what we're doing now.

Q: Does that put us at any disadvantage with careless and aggressive adversaries -- the Russians, to take a case -- people who know we are very hesitant?

A: There may have been situations in which we were not hesitant enough or situations in which it was essential that we move aggressively and quickly and we had to accept that there would be losses of life. If there are situations in which you can avoid that loss of life, I for one am going to try to do that every time. That's my choice.

Q: There is some anxiety in Congress. One encounters it not just on Lebanon, on El Salvador, Honduras. It's the Vietnam quagmire fixation.

A: That syndrome will be probably be with us for a very long time. But we are not guiding our conduct entirely on that. There are many things we should have learned from Vietnam, and oneeis that you cannot have any kind of foreign policy action, military or otherwise, that doesn't have the support of a large majority of the American people. It's a very vital necessity for any action in a democracy. In Vietnam, we pursued a course that did not have that, nor did it have the understanding of the American people. It is essential that we not get into that kind of thing again.

Now, first of all, we have to regain our military strength and capability. We are doing that now, not as rapidly as perhaps we have to but as rapidly as we can. And we're doing it quite effectively, but it will take a long time, six or seven more years of very resolute determination and a willingness to face the fact that there's no way that it can be done without large expenditures, even though those expenditures will never exceed more than 29 percent of the total federal budget. If we do that and if we pursue a firm foreign policy, we can achieve very good hopes for peace. But if in the course of doing that we try to minimize any kind of risk or loss of life to the Americans who are asked to perform those front-line duties, I think that's not only a totally worthy objective but everyone should understand it's the objective that we're going to follow. This does not mean that we're going to be weak, but it does mean that we're going to have a due regard for the value of human life. these Marines. What does this say to you?

A: What it really says to me is that we have the same value for human life that we've always had. That we have the same reluctance to have any of our men in uniform injured or killed. I think that's a pretty healthy thing. The strength that we have to have is a totally different thing. We have to have the ability to have a force that can go in on two days' notice in the Mediterranean and be protected by carrier battle groups and all the rest. We have to have that. That gives us the ability to maintain peace for ourselves and our allies and we've been instrumental in that process for a couple of generations now and we'll continue to be.

But we are very worried about any loss of human life. We recognize that it's inevitable in some situations, as the men who enlist voluntarily in the services recognize that it's inevitable. But you don't court it and you certainly do everything you can to avoid it. The military exists only for one purpose and that's to carry out the foreign policy of the president. The foreign policy of the president is to return peace to Lebanon as quickly as possible, and the way we believe that can best be accomplished, with the least involvement of human life, because there's been far too much loss already, is what we're doing now.

Q: Does that put us at any disadvantage with careless and aggressive adversaries -- the Russians, to take a case -- people who know we are very hesitant?

A: There may have been situations in which we were not hesitant enough or situations in which it was essential that we move aggressively and quickly and we had to accept that there would be losses of life. If there are situations in which you can avoid that loss of life, I for one am going to try to do that every time. That's my choice.

Q: There is some anxiety in Congress. One encounters it not just on Lebanon, on El Salvador, Honduras. It's the Vietnam quagmire fixation.

A: That syndrome will be probably be with us for a very long time. But we are not guiding our conduct entirely on that. There are many things we should have learned from Vietnam, and oneeis that you cannot have any kind of foreign policy action, military or otherwise, that doesn't have the support of a large majority of the American people. It's a very vital necessity for any action in a democracy. In Vietnam, we pursued a course that did not have that, nor did it have the understanding of the American people. It is essential that we not get into that kind of thing again.

Now, first of all, we have to regain our military strength and capability. We are doing that now, not as rapidly as perhaps we have to but as rapidly as we can. And we're doing it quite effectively, but it will take a long time, six or seven more years of very resolute determination and a willingness to face the fact that there's no way that it can be done without large expenditures, even though those expenditures will never exceed more than 29 percent of the total federal budget. If we do that and if we pursue a firm foreign policy, we can achieve very good hopes for peace. But if in the course of doing that we try to minimize any kind of risk or loss of life to the Americans who are asked to perform those front-line duties, I think that's not only a totally worthy objective but everyone should understand it's the objective that we're going to follow. This does not mean that we're going to be weak, but it does mean that we're going to have a due regard for the value of human life.