As the slight, dark-haired man in the blue suit carefully steps down between them, two rows of honor guards in dress uniforms snap unloaded ceremonial rifles to ''present arms.''
The secretary of defense of the United States waits patiently for the visiting head of state. He has done it many times before in this sunny spot outside the Pentagon.
A few moments later, in a vast and finely appointed office, he holds a Revolutionary War powder flask, smiling graciously and patiently showing it to his visitor - the President of Portugal - as press photographers crowd around to record the event.
For one who spends most of his waking hours dealing with the larger weapons and strategies and costs of war, Caspar W. Weinberger seems a man of unusual grace and patience. Perhaps it was his experience as a younger man - honor student at Harvard, platoon leader in the South Pacific - that helped shape the steady character of one charged with rearming America.
But at times, through the veneer of patience and calm and inevitable politeness he shows in the Capitol Hill jungles and press-conference battlefields, can be seen less placid traits. There is a sense of urgency and foreboding here. And it seems to hold him just as firmly as the clasp with the presidential seal which grips his tie.
The United States is facing greater dangers than ever before, he says. And whether or not there is time to turn back this threat of war, he says, is his greatest concern. In a recent Monitor interview, Mr. Weinberger rejected any suggestion that he is, thus, a latter-day Winston Churchill. ''I would like to have his eloquence and skill,'' he says. ''But no one comes even close to that.''
It is true that Weinberger does not rivet audiences when he addresses them. His speeches are more tutorial than inspiring. But what he says, in private conversation as well as in public, makes it clear that he sees his prime role in the Reagan administration as similar to Churchill's in the '30s. And one comes away from a conversation with Weinberger feeling that he is not simply parroting Ronald Reagan's conservative views, as has been said, but is acting on the basis his own most heartfelt beliefs.
In a speech this spring at Westminster College in Fulton, Mo. (where Churchill gave his famous ''Iron Curtain'' address in 1946), Weinberger described himself as one ''who has been an unreconstructed and almost unquestioning admirer of Winston Churchill for nearly 50 years . . . representing a generation that was profoundly affected by Winston Churchill's principles.''
Recalling the former British prime minister's fall from political grace after World War II, he acknowledged that such unquestioning admiration ''may seem more than a little outdated.'' But, like his bulldog hero, any criticism about the wisdom of his beliefs and policies has made Weinberger all the more determined to see that they prevail.
Asked if the US is more secure today than it was when the Reagan administration took office, the defense secretary answers quickly, ''Oh yes, without any question at all.'' He ticks off the improvements in military readiness, personnel recruiting, and major advances in the three legs (B-1 bomber, MX missile, Trident submarine) of the strategic nuclear triad.
But just as quickly, he follows with this sense of urgency and concern about whether the rebuilding of US military forces will come soon enough to deter war - or, should deterrence fail, to limit conflict and conclude it on the best possible terms for the US. ''We don't know how much time we have,'' he says. ''It's always been a great worry with me that we've had time before in previous wars, but barely enough time.''
Weinberger acknowledges that he has had to spend much effort trying to convince Americans (most of whom favor the mutual and verifiable nuclear freeze opposed by the White House) that he does not believe a nuclear war can be rationally fought and won, that he yearns for lasting peace as much as anyone.
''The majority of the people want peace,'' he says. But then, without sounding patronizing, he adds a note of frustration: ''They would like to get it in the most inexpensive way and with the least unpleasant circumstances to think about.''
The expense and unpleasantness of preparing for war (whether or not fighting ever occurs) have dogged Caspar Weinberger since he left his secure and lucrative executive position in California. He rankles, for example, at a recent economic analysis showing that the MX intercontintental ballistic missile program alone will cost each American family $400 and result in net economic losses to 90 percent of all congressional districts.
Such criticism is both inaccurate and irrelevant, he says, pointing to Pentagon research showing that, overall, defense spending helps the economy. ''The fact is, it does have a good effect on the economy,'' he insists. ''But that is not a reason for doing it. You only do it because you need it. Unfortunately, we need a great deal of defense now because we neglected it for 10 years.''
In any case, he argues, the country's largest peacetime military buildup ever (nearly $2 trillion over the next five years) should be measured against the perceived threat. And that, in his view, means Soviet actions and intent. Here, too, he feels this frustration over public perceptions vs. his view of reality.
''The public wants peace and wants to have the belief that you can attain it by dealing in a rational manner with an opponent that is always presumed to be rational,'' he says. ''What we have to realize is that the leadership of the Soviet Union has demonstrated time and again - the Korean air disaster shouldn't have been a surprise to anyone - that they are not governed by any of the philosophies or guidelines or restraints that we impose on ourselves, that they do not conform to our kind of thinking or our kind of belief as to what is proper or improper. They have a different set of values, a totally different set of values.''
In the same way, he is suspicious of the current political rush for arms control agreements. Past accords, he says, have allowed Moscow to continue its nuclear buildup with little restraint.
''That's the whole history of the previous treaties they've agreed to,'' he argues. ''They have not reduced arms. They have tried to limit them generally in ways the Soviets wanted, ways the Soviets would agree to. Because they would agree to them, there was great pressure for us to agree. That made it a 'good' agreement. But the way it has turned out, the limitation has been in ways that the Soviets wanted, and it did not provide for any significant reduction.''
Many nuclear wizards and strategic theorists - the ''experts'' relied on by press and public - say there still is ''rough parity'' or ''essential equivalence'' in superpower strategic forces. They note that even the newest intercontinental missiles deployed by the Soviets are of the less-reliable liquid-fueled variety, that the Kremlin generals can't be sure the rockets won't fizzle or blow up on the launch pad as they have in the past.
But Weinberger looks at the newer generations of Soviet missiles being tested (no political hand-wringing about an MX over there). He worries especially about Moscow's apparent proclivity to use force where it serves political ends - ''their obviously barbaric approach to things compared to our standards and their willingness to use this military power in Afghanistan and in Poland indirectly and so on.''
And - again - he expresses frustration with what he sees as misguided public urgings for greater administration ''flexibility'' at the Geneva arms control talks: ''The desire of the people to get an agreement has led many of them to say we don't really notice particularly whether you have made the best proposal or not. We want an agreement, so you've got to be more flexible.''
Back when Caspar Weinberger was a Harvard undergraduate, the word ''appeasement'' might have accompanied such warnings. It does not today. But the defense secretary does like to recall Winston Churchill's comment that while the British people ''had the lion's heart'' during World War II, it was the late prime minister who was ''called upon to give the roar.'' And while the times and circumstance are not the same, Weinberger, in his own way, is roaring as well.