In the first news conference of his presidency on Jan. 29, 1981, Ronald Reagan summed up his view of the Soviet Union by saying that its goal was world domination and declaring that Soviet leaders "reserve unto themselves the right to commit any crime, to lie, to cheat, in order to attain that . . . ."

Earlier this month, Reagan gave a far different assessment to foreign journalists. Asked if Soviet leader Mikhail Gorbachev was "a real friend," the president replied affirmatively and said, "We can debate and disagree . . . but there is never a sense of animus when the arguments are over."

The symbolic distance between these responses is greater than the 4,876 miles between Washington and Moscow, where Reagan is scheduled to arrive today for his fourth meeting with Gorbachev.

Reagan is riding the crest of an immense change in U.S.-Soviet relations that largely reflects significant differences between Gorbachev and his predecessors. But the change in Reagan's outlook began before Gorbachev took over and has developed rapidly in response to what the president sees as major changes in the Soviet Union. Reagan appears to believe what is happening is a natural consequence of a U.S. policy he calls "peace through strength," but some of those who have watched the president at close quarters say he has changed his opinion of the Soviets more than he realizes.

"Ronald Reagan came into office thinking that everything about Soviet-U.S. relationships was black and white," says a longtime associate. "Now, he has become a master of the gray. That's why he can and does say contradictory things about the Soviets. He sees contradictions and nuances now."

During his presidency, Reagan's rhetoric and approach have evolved from militant distrust for the Soviets to one of almost respectful appreciation for Gorbachev. In private, Reagan once told contemptuous anti-Soviet jokes. Now, he seems to be rooting for Gorbachev to succeed and has expressed sympathy for the problems facing the Soviet leader as he seeks to reform his nation's creaky bureaucracy. At other times, he has told associates that he thinks Gorbachev, an atheist, secretly believes in God.

Once suspicious of all U.S.-Soviet arms control treaties, Reagan now seeks an accord that would halve the nuclear arsenals of the superpowers. Once convinced that accommodation with the Soviets would undermine the American will to keep its defenses strong, Reagan now is presiding with Gorbachev over what both leaders see as a new era in U.S.-Soviet cooperation that could make the Cold War an unpleasant memory.

In a statement to The Washington Post and Newsweek last week Gorbachev praised Reagan's "realism," and asked rhetorically, "Who would have thought in the early '80s . . . that it would be President Reagan who would sign with us the first nuclear arms reduction treaty in history?"

Who indeed? Certainly not Reagan's most conservative supporters, many of whom criticize the president for his summitry and expressed desire to leave a legacy of arms control. Reagan has sought to reassure the right wing by proclaiming that his basic views have not changed. He quotes the Russian words for "trust but verify" so often that even White House aides groan when they hear them.

There is a core of truth to Reagan's claim that he had a long-range game plan aimed at nuclear arms reductions. More than four months before the 1980 election, Reagan said in an interview with The Washington Post that the arms buildup he favored would restore a U.S. military capability that had been declining since the Vietnam War and would lead to serious arms talks. Reagan based his view on the belief that the Soviet economy was too backward for its leaders to compete effectively with the United States in a high-technology arms race.

Reagan had opposed the SALT II treaty, signed by President Jimmy Carter but withdrawn from ratification after the Soviet invasion of Afghanistan, on grounds that it did nothing to reduce nuclear stockpiles. He thought that the doctrine of "mutual assured destruction," known by the acronym MAD, was appropriately named. This view subsequently made Reagan receptive to the concept of antimissile defense and gave rise to the Strategic Defense Initiative (SDI).

Aside from these basic ideas, Reagan held a primitive view of the Soviets that had changed little since the late 1940s, when Joseph Stalin was in power and Reagan was a movie actor and president of the Screen Actors Guild at a time of emotional congressional investigations of Communist influence in Hollywood.

In his 1965 autobiography, "Where's the Rest of Me?", Reagan referred to his encounters with Communists and their sympathizers in Hollywood as the seminal experience in forming his view of communism. Reagan has always been his own best audience, and his stark view of Soviet immorality was reinforced by participation in Barry Goldwater's 1964 crusade for the presidency and again in Reagan's campaign to wrest the Republican presidential nomination from President Gerald R. Ford in 1976.The "Detente" Issue

Reagan began that campaign by emphasizing economic themes. He lost the early primaries to Ford and turned to high-voltage conservative issues in an attempt to rescue his candidacy. Among these issues was "detente," which Reagan saw as a fraud that masked a Soviet military buildup aimed at world domination. The issue was so effective that Ford abruptly announced he was renaming the policy "peace through strength."

Reagan narrowly missed gaining the nomination but his campaign established him as the Republican heir apparent after Ford was defeated. Running against Carter in 1980, Reagan assured voters that he was not "a mad bomber" bristling for confrontation with the Soviets. But at his first news conference after he was elected, Reagan denounced detente when asked his view of Soviet intentions.

"Well, so far, detente's been a one-way street that the Soviet Union has used to pursue its own aims," Reagan said. "I don't have to think of an answer as to what I think their intentions are: they have repeated it. I know of no leader of the Soviet Union since the revolution . . . that has not more than once repeated . . . that their goal must be the promotion of world revolution and a one-world socialist or communist state, whichever word you want to use."

Perhaps the most significant part of that answer was Reagan's admission that he "didn't have to think" about his answer. His anticommunism was by then so ingrained and reflexive that it was taken for granted among his aides. If anything, Reagan's early foreign policy advisers -- Secretary of State Alexander M. Haig Jr. and national security advisers Richard V. Allen and William P. Clark -- reinforced his anti-Soviet stance.

In his first year in office, Reagan focused on a three-pronged attempt to slash income tax rates, cut domestic spending and massively boost the military budget. Foreign policy was secondary, in part because Reagan had heeded the advice of former president Richard M. Nixon to deal with inflation and other economic problems before trying to perform in the international arena.

The president was also cut off from foreign policy issues by a March 30, 1981, assassination attempt that left him seriously wounded and set the pattern for his delegated presidency. Aides brought only the most important issues, most of them domestic, to Reagan for decision. National security briefings were delivered in writing.

While in the hospital, Reagan composed a letter to Soviet leader Leonid Brezhnev that startled diplomatic circles with its seeming naivete. The letter made Reagan's familiar banquet-circuit argument that "government exists for {the} convenience" of people, "not the other way around." Then it launched into a long defense of American conduct throughout the world since World War II and a denunciation of Soviet policy in Afghanistan, Angola and Cuba.

Throughout the next three years U.S.-Soviet relations descended into a pattern of mutual vilification. Reagan did offer a "zero option" plan for removing medium-range missiles from Europe that ultimately became the basis for the Intermediate-Range Nuclear Forces Treaty signed by Reagan and Gorbachev in December. But the original proposal was accompanied by a harsh denunciation of Soviet policies and was widely viewed as an effort to win a propaganda victory rather than an attempt to improve U.S.-Soviet relations.

On March 8, 1983, Reagan delivered what connoisseurs of anti-Soviet rhetoric still consider his touchstone speech. Addressing the National Association of Evangelicals in Orlando, Fla., in a speech drafted by conservative speechwriter Anthony Dolan, the president assailed the Soviets as "an evil empire" and the "focus of evil." He also defended his description of Soviet immorality at his first news conference, adding the insult that he was "only quoting Lenin, their guiding spirit."

By Feb. 25 of this year, in an interview with The Washington Post, Reagan was quoting Vladimir Lenin approvingly to defend Gorbachev's policies of perestroika {restructuring} and glasnost {openness}. Reagan said Gorbachev was different from other Soviet leaders and was trying to carry out Leninist reforms that had been reversed by Stalin.

"Lenin had programs that he called the new economics and things of that kind," Reagan said. "And I've known a little bit about Lenin and what he was advocating, and I think that . . . in glasnost and perestroika and all that, this is much more smacking of Lenin than of Stalin."

Reagan's friends and critics, as well as outside analysts, give varied reasons for the dramatic change in the president's approach. Some see his contradictory statements as part of a clever or instinctive strategy for dealing with the Soviets. Others say that Reagan has changed in office, for better or worse, becoming more conscious of the impact of his rhetoric and more preoccupied with his legacy.

Former deputy chief of staff Michael K. Deaver, who for years was the aide closest to Reagan, gave much of the credit to Nancy Reagan. Some conservatives echo this view and put a darker cast on it, blaming the First Lady for a supposed overeagerness for arms control they claim is motivated by concerns for her husband's legacy.

William Hyland, editor of Foreign Affairs quarterly and a former national security official, expressed belief that pressure from European allies, particularly British Prime Minister Margaret Thatcher, played a significant role in influencing Reagan to deal with the Soviets.

Those who have paid close attention to the dynamics of the Reagan presidency give four basic reasons for the change from "evil empire" to "real friend." They cite the perceived success of Reagan's military buildup, key personnel changes, the president's belief in his negotiating ability and the rise of a Soviet leader who is eager to bargain."This Nuclear Mess"

White House chief of staff Howard H. Baker Jr., an arms control advocate as Senate Republican leader in the first term, recalled that Reagan said to him and House Republican Leader Robert H. Michel (R-Ill.) in 1982, during a low point in U.S.-Soviet relations, "We've got to do something about this nuclear mess." As Baker sees it, "The fundamental instinct was always there, but the tactic and technique have changed considerably."

Spurring the tactical change was Reagan's conviction that he had restored U.S. military power. This view was reflected in a Jan. 16, 1984, internationally televised speech that advocates of improved U.S.-Soviet relations view as the turning point away from the "evil empire" approach. In this speech Reagan called for "a constructive and working relationship with the Soviet Union" to solve world problems, including regional conflicts.

The speech coincided with a meeting between Secretary of State George P. Shultz and then-Soviet Foreign Minister Andrei Gromyko in Stockholm that was aimed at exploring U.S.-Soviet opportunities. It preceded by two weeks Reagan's reelection announcement, in which he stressed his desire to improve the superpower relationship.

By this time the Reagan supporting cast had changed. Shultz, who replaced Haig in 1982, and national security adviser Robert C. McFarlane, who replaced Clark in 1983, were less suspicious of the Soviets and more favorable to arms control than their predecessors. Shultz and McFarlane tactically embraced SDI, hoping to move the arms control deadlock off dead center. By 1985, Reagan was eager for a summit. He would say later that he had always wanted one but that Soviet leaders "kept dying on {him}" during his first four years in office.

When Reagan returned from his first summit with Gorbachev, held in Geneva in November 1985, he compared the Soviet leader to a movie producer he had dealt with during his years of negotiating for the Screen Actors Guild. The analogy and Reagan's positive view of Gorbachev were welcome signals to those who favored serious arms control negotiations with the Soviets.

"There's a distinction between the way Reagan thinks about nation-states and the way he thinks about individuals," said a Republican who knows the president well. "I always thought that the more Reagan had contact with a real live Soviet leader, the more his conduct would differ from the abstraction. And whenever he's in the negotiation mode, there's a good chance of progress."

Reagan felt free to negotiate, observed Hyland, because there was "a feeling among Reaganites that Reagan has been vindicated in his policies." He had been steadfast, and the Soviets had come to him. Gorbachev, said Hyland, was "the clincher."

Stuart K. Spencer, a longtime friend and leading political strategist for the president, offered this synthesis of Reagan's odyssey: "Reagan had a goal of reaching agreement with the Soviets and he played hardball to reach this goal, both with the defense budget and the 'evil empire' speech and the like. It's a very typical Reagan strategy. But the inevitable Reagan luck also played a part . . . . He could have yelled 'evil empire' forever unless Gorbachev or someone comparable came along."

Spencer also said that Reagan, for all his professions of constancy, has been subtly changed by the presidency and by awareness of the terrible nuclear power possessed by the rival superpowers. "No one can remain immune from that," Spencer said. "The job makes you grow."

Washington Post staff writer Don Oberdorfer and researcher Michelle Hall contributed to this report.