To understand the diplomatic maneuverings of recent days (West German Chancellor Schmidt to Moscow, his foreign minister Hans-Dietrich Genscher to Washington, French Presiden Giscard d'Estaing to Bonn) one should start with a military fact:
In 1977 the Soviets began deployment of a new nuclear weapon in the European theater. It was called the SS-20. It was a mobile missile with multiple warheads and its range -- 3,000-4,000 miles -- was well beyond that of previous Soviet land-based nuclear weapons deployed for use in the European theater.
At the end of 1977 Western intelligence sources estimated that 20 of these new weapons had been deployed. The number has increased since at the rate of 50 per year. There are now approximately 120 of these SS- 20 missiles in the Soviet order of battle aimed, or aimable, at targets anywhere in Western Europe.
At the same time the Soviets deployed a new medium- range bomber, the Tu 22 M , labeled "Backfire by Westerners. It has a range of about 3,000 miles and carries five nuclear warheads. Fifty of these are now presumed to be assigned to the European theater.
The appearance of these two new and much longer range Soviet weapons in the European theater caused anxiety among the West Europeans and urgent consultations about the desirable answer. NATO had many nuclear weapons on its side targeted on Soviet installations in Eastern Europe. But the land-based NATO weapons of 1977 did not have the range to penetrate inside the frontiers of the Soviet Union itself.
Previous to 1977 there was a more or less equal balance of short-range missiles in the European area underneath the great umbrella of US superiority in long-range strategic weapons. Europe could be presumed to be reasonably safe as long as the US enjoyed superiority ove the Soviets in the stratosphere.
But since 1977 the Soviets have continued to narrow the gap in long-range nuclear weapons until they now enjoy "equivalence" -- some say superiority. Under that umbrella of official "equivalence" a steady increase in Soviet middle- range weaponry in the European theater takes on extra weight and meaning.
Could NATO afford to allow the Soviets to sit back with their SS-20s and Backfire bombers inside the Soviet Union while NATO had nothing similar in Western Europe which could penetrate to the bases of those new weapons? NATO members began talking about new weapons of similar range -- 3,000 to 4,000 miles -- to balance off the new Soviet weapons.
The Soviets saw that inclination in NATO circles, and tried to head off a NATO decision. On Oct. 6, 1979, Leonid Breshnev made a speech in East Berlin offering to cut back on Soviet nuclear weapons based in Europe provided NATO would decide against new NATO weapons. But he did not offer to dismantle the SS-20s or scrap the Backfires.
The Brezhnev speech did not seem in NATO circles to be sufficient to NATO's safety. The NATO foreign ministers gathered in Brussels and decided, on Dec. 12 , to modernize NATO's European theater nuclear forces by deployment of 108 US Pershing II medium-range missiles and 464 US ground-launched cruise missiles. Both of these new weapons would have the range to reach targets inside the Soviet Union from bases in Western Europe.
The new American weapons (the Pershing IIs and the cruise missiles) will be ready to start deployment in 1983. Since NATO's decision of last Dec. 12 Soviet diplomacy has been aimed at inducing the NATO countries to reverse it and thus prevent the deployment of the new weapons.
The present time, and without the proposed new US weapons in Europe, the Soviets have a nuclear advantage in the European theater. They have 5,364 launch vehicles (ground, sea, and air) against 2,045 for NATO. In warheads presumed to be available they stand at 2,244 against 1,811 for NATO. There is a complex formula used by the International Institute of Strategic Studies which factors in such things as quality, performance, and other intangibles. Under this IISS formula the Soviets have a "system utility figure" for the European theater 1,209 against 1,065 for NATO. If the SS- 20s and the Backfires were removed the soviet advantage would disappear.
It is desirable for the security of Western Europe that one of two things happens between now and 1983. Either the Soviets remove their SS-20s and Backfires from the European theater, or NATO deploys the new American weapons which would balance off those Soviet weapons.
But the Soviets, obviously, prefer to have things remain as they are. This existing condition means that there is a mutual balance in intercontinental strategic weapons between the US and USSR which more or less neutralizes big umbrella is Soviet superiority in European theater weapons. If this condition is allowed to become permanent, the Soviets presumably have the prospect of neutralizing and dominating Western Europe.
So, does everyone talk?
Until Chancellor Schmidt went to Moscow the Soviet position was that they would negotiate on theater nuclear weapons provided, first, that the US Senate ratify SALT II and, second, that NATO cancel its decision to deploy the Pershings and cruise missiles.
Both those preconditions were unacceptable to the NATO countries. So no talks were possible so long as Moscow stood to that position.
In Moscow on July 1, Chancellor Schmidt thought he heard Mr. Brezhnev agree to drop those preconditions. But if he did (which remains to be confirmed) what did he get in return?
Answer: Afghanistan has been pushed to the back burner of international discussion and attention. Which, of course, is a gain for Moscow.