Washington — While the superpowers pick over each other's arms control positions, angling for the ''more flexible than thou'' spot in world opinion, the most difficult issues in meaningful nuclear weapons reductions have yet to be addressed.
As President Reagan implied in his speech to the United Nations this week, verification of weapons counts and compliance with arms treaties will be the key to any agreement. So far, as Defense Secretary Caspar Weinberger told the Monitor recently, ''there has been very little talk of verifiability.''
The issue will become increasingly important as smaller, mobile weapons (like easy-to-hide, ship-borne cruise missiles) enter both sides' arsenals in large numbers.
Until now, the Reagan administration has been reluctant to charge the Soviet Union with violations of existing arms treaties. One of the criticisms of the unratified SALT II agreement is that it contains many loopholes through which the testing and development of new nuclear missiles can pass.
That changed a bit this week when Mr. Reagan cited new Soviet missiles and radar facilities that ''raise serious concerns about Soviet compliance.'' Pressure to speak out this way is growing, particularly after the downing of the South Korean airliner by a Russian interceptor. A bipartisan majority in the Senate has told the administration to make public Soviet treaty violations.
Meanwhile, the separation of strategic (intercontinental) and intermediate-range forces in arms control talks at Geneva is another block to significant reductions in nuclear arms. Many experts consider this division an artificial one that creates more problems than it solves.
A group of former US arms control officials Tuesday announced arms-reduction proposals that would eventually merge the two sets of talks and more indirectly address the important question of verifiability.
Written by Gerard Smith (chief SALT I negotiator and former director of the Arms Control and Disarmament Agency), Paul Warnke (also a former ACDA director, who was the chief US SALT II negotiator), and John Rhinelander (legal adviser to the SALT I delegation), these proposals seek to increase nuclear stability by reducing the quantities and qualities of weapons on both sides.
This plan envisions two phases. During the first phase, the Soviet Union would have to dismantle 378 of its multiwarhead land-based intercontinental ballistic missiles and 160 of its new SS-20 intermediate-range missiles. Other missile cuts would be required as well.
There would be incentives for the Soviets to shift away from their heavy dependence on these most-threatening, land-based missiles to a greater proportion of weapons on aircraft and submarines. Here, Moscow would have to halt testing and deployment of its new SS-X-24 missile.
Likewise, the US under Phase I of this plan would have to halt the testing and deployment of the MX, which many experts consider destabilizing because of its extended range, heavy payload, and high accuracy. The US would also halt the planned deployment of the Pershing II intermediate-range missile in Europe and defer the deployment of the planned ground-launched cruise missiles there. The US would be allowed during Phase I to deploy B-1 bombers, develop a new single-warhead ICBM, and replace older submarine missiles with newer models.
The essential goal during this 10-year interim period would be to shift superpower nuclear arsenals away from the most threatening yet most vulnerable weapons (generally, multiwarhead land-based ICBMs) that put both sides on a ''hair trigger.''
This direction was urged by the President's Commission on Strategic Forces (the Scowcroft Commission) in its report last spring. Messrs. Smith, Warnke, and Rhinelander would allow more time and greater incentives to the Soviet Union to do this than does the current Reagan administration proposal at the strategic arms reduction talks (START).
During Phase 2 of their plan, intermediate-range missile and START talks would be combined. Emphasis would further shift from counting launchers to counting warheads and bombs, as the Scowcroft Commission urged. Reductions below the first-phase limits (especially those on multiwarhead missiles) would continue to be negotiated.
Smith, Warnke, and Rhinelander are less specific in their recommendations on the difficult area of verifiability. They would resolve part of the problem by banning the testing of all sea-launched cruise missiles (SLCMs) from submarines and long-range SLCMs from surface ships.
Under current agreements, information broadcast from test missiles may not be encoded if it deals with negotiated test limits that other countries should be able to verify. These former officials would like to ban any encryption of such flight-test telemetry. Open missile testing is unlikely to be acceptable, especially if (as has been charged) the Soviet Union is testing new missiles in violation of existing agreements.