Although he waited a long time to deliver it and met with a lot of criticism for the delay, President Reagan's first major foreign policy address yesterday was a masterful performance that took the high ground in the quest for nuclear arms control. It was a speech that could wind up changing the tone of his administration and the way it is perceived by worried friends in Europe and foes in Moscow.

Absent from this address was the sense of belligerency toward Moscow that has characterized many earlier public utterances by the president and members of his Cabinet. The president told the Soviets he wanted to negotiate News Analysis sizeable reductions in armaments across the board--in long-range strategic forces, missiles based in Europe and even conventional armies facing each other across the German border.

But he did not threaten Moscow with a new arms race as the price for disagreement, as he has in the past.

The president said all the right things to calm America's traditional allies in Western Europe, many of whom have become increasingly alarmed by this administration's seemingly endless off-the-cuff and frequently ill-timed comments about fighting a nuclear war.

In proposing elimination by both sides of planned or existing nuclear-tipped missile forces in Europe, the president adopted a position that has been favored more by the West Europeans than by many members of his own administration for a long time. This could turn out to be the most significant aspect of the speech: it showed a U.S. administration willing to adopt the views of its allies on a key question of American national security policy.

The Europeans, in a sense, have pushed the president onto a course that he may not have envisioned even six months ago. If the reaction to what the president has said is good, both here and abroad, then it could help cement this administration into a policy in which arms control and dialogue with Moscow play a larger role than had been anticipated.

What also lies behind the president's approach is an assessment at the top levels of the American government, including the intelligence community, that the situation in Western Europe is serious in terms of new currents flowing that could change the way Europeans have viewed the United States since World War II.

The president showed that he understood what was happening. Rather than attack the pacifist and neutralist demonstrators who have often directed their protests at this country rather than at the Soviet Union, the president sought to bridge the gap between generations. He talked of how twice in his lifetime Europe had been ravaged by war and how those who lived through those troubled times "share a common appreciation" of the western NATO alliance that emerged from that war-torn era and how it has managed, through military preparedness, to help preserve peace for the past 35 years.

Today, he said, a new generation is emerging on both sides of the Atlantic whose members don't remember the importance of that alliance in the immediate post-war years and many of whom "do not fully understand its roots in defending freedom and rebuilding a war-torn continent." Still, the president said, he understands their concerns, and their questions deserve to be answered.

He tried to answer them by reiterating some old alliance policies: that an attack on one is an attack on all, that deterrence is the best way to prevent attack, and that no NATO weapons--conventional or nuclear--"will ever be used in Europe except in response to attack."

He also tried to explain the key reason the alliance believes the new U.S.-built Pershing II and cruise missiles are necessary for deterrence if no arms reduction agreement is reached. Although the Soviets have more than 600 intermediate-range missiles able to fly from deep inside the Soviet Union to Western Europe, the West, at the moment, has no such missiles based in Europe. The idea behind the new weapons, which can quickly reach Soviet soil, is not only to counter the Soviet weapons but to let Moscow know that the Soviet homeland would not escape attack from Europe if it attacked Europe. In addition, these weapons are supposed to keep intact the "vital link" to the big ocean-spanning missile forces based in the United States.

During the months that anxiety has been developing in Europe about these weapons, no top American official has tried to explain to the European public why these weapons are needed in any deeper sense than as a numerical counter to the Soviets.

The Soviets clearly will not find Reagan's proposals acceptable. The Soviets would, in effect, have to dismantle hundreds of their front-line missiles in return for the West refraining from a deployment that has not begun and is politically vulnerable to being overturned by opposition in the countries where the weapons are meant to be deployed.

The Soviets also view these U.S. weapons in a dramatically different way. Because the Pershing and cruise can strike the Soviet homeland, while Russian SS20, SS4 and SS5 missiles cannot reach the United States, the Soviets see the NATO buildup as a subterfuge for the United States being able to wreak more havoc on the Soviet Union without having to account for it in any assessment of the strategic balance of intercontinental-range forces between the two superpowers.

It will also undoubtedly be noted by Moscow that the president, in a generally overlooked portion of the new strategic arms buildup he announced on Oct. 2, said the United States would deploy "several hundred" nuclear-armed cruise missiles on submarines. Although U.S. officials insist these would not be meant as replacements for the cruise missiles planned for Europe, the Soviets probably will not see it that way.

Nevertheless, the sweeping Reagan proposals revealed yesterday clearly are a serious starting point and are already being endorsed wholeheartedly by European leaders such as West German Chancellor Helmut Schmidt, who has been the key allied player in this situation for several years. If the European public agrees, then Moscow undoubtedly will have to make equally serious counterproposals and a process will be under way which, however complex and difficult, could change the shape of both opinion and security in Europe.

Early in 1977, the Soviets sharply rejected proposals by the Carter administration to sharply reduce the strategic missile forces of both sides. These proposals were rejected in large measure because they were greatly at variance with agreements for more modest limitations that had been worked out with the Ford administration but never ratified.

While the Reagan proposals also call for deep cuts in many forms of arms, it is clear that this philosophy is integral to the Reagan approach and not some radical idea which the Reaganites will easily abandon. This, too, could make the Soviets at least regard the proposals more seriously. "We do not want a repetition of past disappointments," the president said. "We do not want an arms control process that sends hopes soaring only to end in dashed expectations."

For good measure, Reagan also reminded his listeners in Europe, including the doubting younger generation, that Moscow still retains a vast army in East Germany (roughly 220,000 men in 20 divisions, according to western estimates), bigger than the allied invasion force that landed in France in 1944. He suggested that cuts in that kind of force could make a convincing contribution to peace in Europe.

Although he didn't specifically say it, the implication is that the United States might also reduce its forces in the West, another issue of extraordinary potential importance that has not been discussed seriously for many years.