Washington — Sam Nunn appears to have the White House by the tail. Determined to stop the Reagan administration's efforts to reinterpret the 1972 Antiballistic Missile (ABM) Treaty, the Democratic senator from Georgia and chairman of the Senate Armed Services Committee has launched a counteroffensive that augurs a vigorous battle between Congress and the executive branch.
The stakes are high. Involved are President Reagan's efforts to achieve arms control agreements with the Soviet Union - on both medium-range and strategic nuclear arms - and to hold another summit meeting with Soviet leader Mikhail Gorbachev. United States Secretary of State George Shultz and Soviet Foreign Minister Eduard Shevardnadze begin three days of talks tomorrow on the subject.
But even as the Shultz-Shevardnadze meetings get under way, Senator Nunn stands in the shadows like an 'eminence grise, warning the President that he will not support ratification of an accord on reducing intermediate-range nuclear forces, the so-called INF agreement, unless the administration climbs down from its position on the ABM Treaty.
State Department legal adviser Abraham Sofaer has now issued all three parts of a study of the treaty, maintaining that the negotiating record and subsequent practice (i.e., US and Soviet statements of interpretation) point to a ``broad interpretation'' of the pact.
Mr. Reagan adopted this new legal reading because it would allow more latitude for the testing and development of his controversial Strategic Defense Initiative (SDI) program.
The Soviets, for their part, say that SDI is blocking a US-Soviet agreement on strategic-arms reduction.
They insist that the United States must continue to abide by the narrow or traditional view of the ABM Treaty, which does not permit the testing, development, or deployment of exotic space-based defensive systems.
Mr. Nunn, a conservative who has become the Senate's leading expert on defense, takes strong issue with the administration.
Based on his own exhaustive study of the ABM negotiations and subsequent practice, he maintains that the traditional interpretation of the treaty followed by every administration since 1972 is the correct one.
If the White House insists on its position, Nunn warns, he will ask for the entire negotiating record on INF before giving his support to ratification.
Nunn had also vowed to block Senate action on the nomination of Robert Bork to the Supreme Court until GOP senators stop holding up the 1988 defense bill, which contains language requiring congressional approval for any reinterpretation of the ABM Treaty. But faced with that threat, Senate Republicans, at White House bidding, caved in and last Friday voted with the Democrats to take up the defense bill.
As the legislation is debated, Nunn has strong backing for his views among independent arms experts, including former US officials. Three negotiators of the ABM Treaty have strongly criticized the just-issued third part of the Sofaer report as containing distortions and conjectures. (The first and second parts of the study dealt with the negotiating record and the ratification process. The third concerns subsequent practice.)
``We've got 113 pages to explain very few lines of a treaty, and most of them are about expressions of opinion by a few dissenters in the United States government,'' said Gerard Smith, who headed the treaty negotiating team. ``There is absolutely no reference to any explicit statement by Americans or by Soviets that is contrary to the traditional interpretation of the treaty.''
Ambassador Smith warned Friday that the report will make it harder to achieve a strategic arms accord.
Echoing this view, John Rhinelander, who was legal counsel to the delegation, and Raymond Garthoff, senior adviser to the team, note that the Sofaer study conspicuously omits statements by key Soviet and American officials made since the treaty was signed. Among them is a statement by Marshal Sergei Akhromeyev, chief of the Soviet general staff, explicitly supporting the traditional interpretation of the treaty, a statement made months before the administration announced its legal shift.
Even some US arms officials are distraught over the Sofaer documents. The legal case put by Judge Sofaer is seen as part of a campaign mounted by conservative forces in and outside the administration to ensure the future SDI.
The looming confrontation over ABM is significant because of its impact on arms control.
Mr. Reagan has within his grasp not only an INF agreement but an accord calling for large reductions in the superpowers' arsenal of strategic or long-range nuclear weapons.
Yet, to the dismay of many arms experts, he risks missing this opportunity for an agreement because of his exaggerated vision of the Strategic Defense Initiative and reinterpretation of the ABM pact in order to pursue it.
There are no signs that the President is prepared to give ground, even though some of his arms advisers favor such a course, and independent studies conclude that SDI technologies are decades away from being ready to deploy.
What the US wants Moscow to do is ``delink'' SDI from a strategic arms agreement.
But such a move is difficult for the Soviets as long as the administration insists on reinterpreting the ABM Treaty and going ahead with SDI testing that Moscow finds objectionable.
Some US officials suggest that, despite the turmoil over ABM, a strategic weapons agreement is possible, given the political will on both sides.
``There is enough American flexibility ... to preserve SDI without giving away the store, and satisfy the Russians,'' says one State Department official. ``It all depends on how ideological things get and how much the President wants to move.''