Out of the Washington summit comes one overriding message: Mikhail Gorbachev is determined to improve Soviet-American relations, and he can count on Ronald Reagan's help in this task. Other nations will now have to adjust their policies to the new diplomatic reality created in Washington this week.

The debate will and should continue over the Soviet leader's motives in seeking an era of reconciliation. (It walks, talks and sounds like detente but must carry some other, un-Kissingerian name.) Gorbachev yielded little of real substance here while he was scoring public opinion gains that will come in handy if he and his Politburo colleagues decide to squeeze Reagan on Star Wars when he is on their turf next year.

Rather than confronting Reagan over the divisive question of space-based missile defenses, as he did in Geneva and Reykjavik, Gorbachev was content to skirt the issue and to accept in good grace slippery formulations about the Antiballistic Missile Treaty. He lent his authority to the appearance of progress on the next round of strategic arms talks. And he joined Reagan in rounding off other sharp points of dispute in public.

These moves, following the signing of the INF treaty, will combine to persuade other nations that a turning point in Soviet-American relations was reached here, a development that will dramatically affect the existing international order. This is perhaps the primary way in which the Washington summit changed the world this week.

Unlike detente, reconciliation is being shaped in isolation by the superpowers and perches on an even narrower conceptual and diplomatic base. Reagan and Gorbachev will have to fill in the blanks in their new joint vision as they move toward another summit.

China was the third point of the balance-of-power triangle that Nixon and Kissinger consciously created in launching detente and successfully playing Moscow and Beijing off against each other. But Beijing has been absent this time from the calculations of both superpowers.

Beijing is likely to respond by increasing slightly its receptivity to Gorbachev's overtures for better relations. If the Soviet ruler can show that he is making progress on getting Vietnam to begin real withdrawals from Cambodia, the stage could be set for a significant thaw. But China's commitment to continuing the four modernizations, part of its exclusive focus on domestic economic policy, means that Beijing's leadership will make sure that any such improvement does not come at the cost of its ties to the West, source of needed technology and investment. That at least must be the hope of U.S. policymakers.

The Chinese and other American friends or allies will inevitably be nervous about the possibility of quick, large swings in U.S. policy that will be driven by the new relationship with the Soviet Union. They are not likely to have been reassured by the way the summit unfolded, in contrast to the justifiable pride and hope most Americans will have drawn from the impeccable hosting of the Gorbachevs by the Reagans here.

For, despite the president's defensive assertions on Thursday night that "Soviet-American relations are no longer focused only on arms control issues," this was an arms control summit -- the kind the Soviets have always insisted on and the kind that Ronald Reagan used to say he would not participate in, back in the days when he agreed with the analysis of Jeane Kirkpatrick and others that the causes of U.S.-Soviet tensions could not be removed without changes in Soviet behavior on human rights, regional conflicts and other issues.

The joint communique issued in the name of the two leaders devoted precisely one sentence to human rights, indicating in 22 words that no progress had been made. On Afghanistan, the Persian Gulf, the Middle East and other conflicts, Gorbachev made it clear in his press conference when pressed by reporters that it had been a dialogue of the deaf inside the White House, an assessment confirmed by U.S. officials.

Gorbachev's toughness on these issues contrasted sharply with Reagan's moving summation Thursday night, in which the president praised both sides for "moving away from the so-called policy of Mutual Assured Destruction by which nations hold each other hostage to nuclear terror." He then added a phrase that is likely to stir anxiety in Europe, noting that "we are saying that the postwar policy containment is no longer enough. . . . " The contrast between Gorbachev's tough efficiency and Reagan's open sentimentality is one that will cause ripples to spread on the world scene in the months to come.