MOMENTUM toward a midrange missile pact this fall continues to gather. West Germany's decision to allow its 72 Pershing 1A's to obsolesce on the vine, so to speak, and a removal of verification obstacles by Washington and Moscow, have brought agreement nearer. Basic European security concerns would remain, partly as a result of progress toward an accord. If midrange missiles were removed under the ``double zero'' formula being worked out in Geneva - eliminating worldwide all superpower intermediate-range nuclear (INF) missiles with ranges of 500 to 1,000 kilometers and 1,000 to 5,500 kilometers - this would heighten the exposure of the two Germanys as the focus of potential conventional-force warfare. The Soviets will likely press harder for equal cuts in conventional forces between East and West, which the United States sees as strengthening the Soviet bloc's conventional edge, because the East bloc starts with such numerical advantages. Europeanists fear a deepening ``dissociation'' between America and Western Europe, with Americans wanting to reconsider the size of the US troop presence in Europe and other commitments.
How can these concerns be answered?
Long-range nuclear arms would remain, even should negotiations on reductions on these armaments succeed, and some considerable nuclear umbrella would remain. The same argument of US abandonment of Europe is raised by development of the American ``star wars,'' or space defense system: This suggests the fear of dissociation clings to any change from the armaments status quo.
The political logic is clearer.
A midrange missile agreement would confirm Mikhail Gorbachev's credentials as a superpower negotiator. Most of the change in style and tempo in Soviet-US relations has come from the Soviet side, after the relatively young Gorbachev took over from his doddering successors. Whatever the depth and staying power of his glasnost liberalizations and economic reforms prove to be, an impression has been made of an invigorated Soviet leadership.
The American system too, however, is about to undergo its own political rejuvenation with the start of a new political cycle. Whatever advantage Gorbachev has as the new leader on the block could be matched by a new round of initiatives and explorations on the American side beginning in 1989. An INF accord this fall would remove the issue from the domestic political debate, despite skeptics' objections.
For President Reagan, an agreement actually reducing the numbers of nuclear weapons, rather than slowing their growth, would be historic. He, the Soviets, and the West Germans see the sense of this. As do we.