PRESIDENT REAGAN's Guild Hall speech, delivered last Friday in London, powerfully linked his impressions from Moscow with his convictions of a lifetime. The ``faces of hope,'' the possibilities of ``lasting change,'' which he saw in the Soviet capital were, in his view, inseparable from the determination of Western leaders to stand by their principles. There's room for honest disagreement over just how those principles - individual liberty, equal opportunity, respect for the rights of others - are best applied domestically and internationally. Politicians, in the United States and the United Kingdom, wrestle with these differences constantly.
With Mikhail Gorbachev's efforts to ``democratize'' his sprawling nation, that wrestling with democracy has moved to a larger stage, with sharper differences over just what this form of government means. What Mr. Reagan seemed to say in his London speech, with his call for ``a strategy of vigorous diplomatic engagement,'' is that the West should play a continuing role in aiding the Soviets' move toward a more open political environment and a more productive economic one. ``We must do all we can to assist it, and this means openly acknowledging positive change and crediting it,'' the President said.
With typical Reagan optimism - albeit applied to an area he used to reserve for dark warnings - the President looked ahead to a time of recognizing and resolving ``fundamental differences with our adversaries.''
Yes, ``adversaries,'' even though Reagan went out of his way while in Moscow to use the word ``friends.'' That ambivalence indicates how sensitive the task ahead is likely to be. The chief adversary/friend, Mr. Gorbachev, has made clear his irritation with American prodding on human rights failings in the Soviet Union.
The President's main ally and philosophical colleague in a new diplomatic engagement with the East is, of course, Britain's Margaret Thatcher. He glowingly praised her ``valor and strength'' as a champion of free-market democracy. In the historic Guild Hall, Reagan voiced his comfort in being back on the soil of a nation that has remained ``steadfast for what is right and against what is wrong.''
Mrs. Thatcher was the first Western leader to recognize that Gorbachev represented a new generation of Soviet officials. In that sense, she helped set the stage for Reagan's openness to a more constructive era of US-Soviet relations.
As the pomp and circumstance of the summit and its aftermath in London recede, perhaps one of the more enduring legacies of Reagan's summit trip will be a heightened awareness of the value of trust in East-West relations.
The President reiterated that nations do not distrust each other because they are armed; they are armed because they distrust each other. That has the ring of a clich'e, but there's truth in it. Hence the importance of the strict on-site verification measure embodied in the INF Treaty, as well as the confidence-building measures on nuclear weapons tests and missile tests that he and Gorbachev agreed to. The increase in the numbers of young people who will be allowed to participate in student exchange programs is another step toward greater understanding and trust.
Lasting trust in East-West ties cannot rest on results of one US-Soviet summit. It must be earned moment by moment, built on a foundation of actions that back up the words, smiles, and handshakes.
Those actions involve more than negotiations that lead to formal agreements. As President Reagan noted in London, they also involve a willingness to stand by the broader values that motivated postwar allied leaders to form the Western alliance. When the Soviets deal with the West, they need to be able to trust in the West's readiness to deal fairly with them. They must also be able to trust that the alliance will refuse to abandon democratic ideals and legitimate security interests in exchange for smooth relations.