The nuclear deadlock between the superpowers is not only over forging new arms control agreements. It is also over complying with existing ones. A new White House report, due to be released before the end of the year, will charge that, at the same time the Soviet Union has been pressing the United States to comply with the 1972 Anti-Ballistic Missile (ABM) Treaty, it has continued systematically to violate that agreement. The report will say that the Soviet Union could be making strides toward creating its own missile-defense system.
Also, the report is likely to charge that a new Soviet missile - the SS-25 - has 20 times the additional nuclear ``throw-weight'' permitted by the second Strategic Arms Limitation Treaty or SALT II.
The report is expected to claim that the Soviets are continuing construction on a major radar installation in Siberia that the Reagan administration alleges is a clear violation of the ABM Treaty.
``The radar is still there. They have not taken down this huge chunk of concrete and electronics,'' says James McCrery, strategic-programs officer with the Defense Intelligence Agency.
The document - the President's annual report to Congress on Soviet treaty compliance - is due out by Dec. 1. Officials involved in preparing it say it will be delayed, however, while experts debate whether to include new charges of noncompliance by Moscow.
The report is likely to fuel the political debate over arms control, especially as the Reagan administration moves toward deliberately breaching the SALT II Treaty. This will occur when the US deploys one more American bomber armed with nuclear-tipped cruise missiles, as the administration has said it will do soon.
In three earlier reports, the administration has charged the Soviet Union with violating a number of arms control agreements, including the SALT I, SALT II, and ABM Treaties. Soviet cheating is a principal reason put forward by President Reagan for abandoning the SALT II Treaty.
Experts outside the administration concede that the Soviet Union has probably undermined some past arms control agreements, in spirit if not in fact, by exploiting ambiguous wording and hewing to its usual secretiveness about its military planning. But many doubt that the violations are serious enough to warrant abandoning the SALT II or ABM Treaties.
The administration's critics argue that it seems less interested in gaining treaty compliance than in finding justification for abandoning existing arms control agreements.
This year, new charges could be added to the list of Soviet violations as a result of the latest findings.
``I suspect that there will be additional issues raised in that report, over and above those [raised] in the past,'' says Frank Gaffney, deputy assistant secretary of defense for nuclear forces and arms control policy.
Mr. Gaffney and Mr. McCrery made their comments at a public forum sponsored by the Heritage Foundation.
There is disagreement within the government - chiefly between the Central Intelligence Agency and the Defense Intelligence Agency - about the military significance of the latest findings.
Over the past year, one senior US official says, US intelligence sources have picked up ``new and disturbing'' evidence of new Soviet violations of a number of arms control agreements. Another official, however, says there is ``not much new'' - other than continuing evidence of the two ``significant'' Soviet treaty violations - the SS-25 and the Krasnoyarsk radar.
Even critics of the Reagan administration's arms control policies concede that the Krasnoyarsk radar is probably in violation of the ABM Treaty, although they disagree over its military importance.
Krasnoyarsk is ``at the top of the list'' of apparent Soviet violations of arms control treaties, says Michael Krepon, senior associate at the Carnegie Endowment for International Peace.
The US has pressed the Soviets to stop construction of the Krasnoyarsk facility, but to no avail. President Reagan cited the Krasnoyarsk radar last month in his speech about the Reykjavik summit as an example of Soviet noncompliance with arms control treaties.
To many observers both inside and outside the administration, Krasnoyarsk and other apparent Soviet treaty violations call into question continued US adherence to arms treaties.
``The record is not good,'' says James T. Hackett, editor of the Heritage Foundation's National Security Review. ``It's quite clear that the Soviets have as a matter of course violated treaties when it's in their national interest.''
A government official, who asked not to be named, says, ``I don't know how we can be asked to continue complying with the ABM Treaty in face of such obvious Soviet violations.''
But another official, in a different agency, says the administration is trumpeting Soviet noncompliance as an example of perfidy, instead of trying to resolve disagreements through diplomatic means.
``If there was a real desire to make arms control work, you could find a way through the forest,'' this official says. ``But if the desire is simply to hang the albatross around the Soviets' necks, then you never give instructions ... to try to resolve these matters.''
Soviet military officials claim that the Krasnoyarsk radar is to be used for ``space tracking'' - monitoring satellites and other objects in space.
But a Pentagon analyst says the Krasnoyarsk facility is identical in design to the radars designed to give early warning of a missile attack. Under the ABM Treaty, such radars are only to be constructed on the ``periphery'' of each country, facing outward. The Krasnoyarsk facility is in the interior of the Soviet Union, some 500 miles from the nearest border, and faces toward the north.
US experts say it is conceivable that the facility could be used for space tracking, but they add that it is an expensive and poorly placed radar for that purpose.
US analysts are also concerned about Soviet construction of two new large phased-array radars which, together with other recent Soviet moves, could theoretically provide the basis for a nationwide ABM system. One such move: continued testing of SA-12 missiles which, the US believes, could be aimed not only against bombers, but also against cruise missiles. Such a ``dual purpose'' weapon is prohibited by the ABM Treaty.
Some analysts are unconvinced, however, that the Soviets are actually attempting covertly to assemble an ABM system. What they may be doing, one expert suggests, is assembling a variety of weapon systems - some of which skirt existing treaties - as an ``insurance policy'' against a US disavowal of the ABM Treaty.
Clearly, the compliance issue has become highly politicized.
``The Soviets have decided not to make it any easier for the administration to get out of these agreements,'' Mr. Krepon says. ``But they haven't gone out of their way to clear these problems up, either.''
Some analysts are concerned that two construction sites - one near Dushanbe, in Soviet Central Asia - could be the precursors of new high-energy laser weapons, leading to even wider disagreements over new weapons systems.
Compliance with treaties is ``by no means a lost cause,'' Krepon says. ``This problem can be solved, but it will take a different attitude on the part of the Reagan administration to solve it.''