President Reagan used well the forum of the United Nations in addressing the question of missiles in Europe. He showed, to all but the most determinedly skeptical, that he would prefer a Soviet-American agreement limiting Euromissiles to a new American deployment countering Soviet missiles already deployed. Belying his sometime reputation for rigidity, he took the propaganda high ground--on an issue where public support is critical to negotiating success--by airing three new initiatives designed to address concerns the Soviets had raised at the bargaining table.

In the focus on the particulars, people sometimes lose the larger outlines. The single reason there is a Euromissile issue at all is that in the 1970s the Soviets could not resist trying to steal a march on NATO by unilaterally modernizing the intermediate-range nuclear forces (INF) whose political shadow falls most darkly on Western Europe. This foolish and shortsighted misreading of the Western temper produced Europe's demand for the United States to lift that shadow--either by negotiating limits on Euromissiles or by deploying new American missiles on the continent.

It is highly doubtful that Mr. Reagan's latest initiatives will draw Moscow into an INF agreement before the alliance-set December date when the new American deployments are scheduled to begin. But the aura of American reasonableness projected by the initiatives should help make deployment politically easier for the countries about to put new missiles on their soil.

The interesting question is whether, after NATO governments have shown they can deploy over the objections of militant minorities, the Soviets may decide to shave their losses by deflating the Euromissile issue. Regrettably, the Kremlin has complicated such a turn by committing itself to unspecified countermoves against any new American Pershing II and cruise missiles that are deployed.

It is exceedingly important, however, for the INF issue to be moved off center stage so that Washington and Moscow can give their full attention to START. INF covers quite limited numbers of lesser missiles that are sensitive in Western alliance politics but won't make much military difference in the end. START covers large numbers of the most vital, destructive and expensive weapons touching the ultimate security of both sides. It is important to deal effectively with the Euromissile issue, but it is no less important to see it in scale as secondary.