WEST GERMANY has removed a major potential barrier to the administration's first nuclear arms control agreement with the Soviet Union. It has accepted the ''double-zero option'' proposed by Moscow and already informally endorsed by Washington. Double-zero means eliminating in Europe the medium-range missiles of the two great powers and the shorter-range missiles possessed only by Moscow. Considering the centrality of the issue to their security and peace of mind, the Germans acted expeditiously; less than two months have passed since Moscow made its offer.

For the Germans it was a difficult but necessary decision. The left pushed on Chancellor Helmut Kohl from outside his ruling center-right coalition to accept the deal, but inside the coalition the ''steel helmet'' right sought a far-reaching revision of its terms. The conservatives argued that key lower nuclear rungs were being removed from the theoretical ladder of escalation, allegedly ''decoupling'' Germany from American protection and leaving deterrence resting on battlefield nuclear weapons that would be exploded on German territory alone.

The United States has the thousands of other nuclear weapons -- and the strategy and the record -- to rebut these contentions, and it did. What carried the day in Bonn, however, was the judgment of Foreign Minister Hans-Dietrich Genscher. German security finally depends more on solidarity with the United States than on any particular formula of deterrence, he argued; Bonn could not possibly block a major arms control agreement favored by a conservative administration in Washington.

The Germans insist they be allowed to retain -- and evidently soon to replace -- their 72 aging short-range Pershing 1A missiles. These are hybrids meant to give nonnuclear Germany a bit of the feel, with no substance, of nuclear status. The missiles are German and hence formally outside an agreement on Soviet and American intermediate nuclear forces; their warheads are American and hence presumably inside.

There are the makings of an impediment here. But it is hard to think a real hitch could be allowed to develop over a set of old, deteriorating weapons that had escaped general notice before. The real European security interest lies in moving on from reducing missiles to removing the ominous Soviet advantage in the attack capability of conventional forces.