A secret memorandum that the Pentagon brass refused to give the Senate reveals that the Joint Chiefs of Staff a year ago set specific conditions for U.S.-Soviet negotiations on SALT II, then endorsed a treaty that failed to meet their requirements.

JCSM-321-78, sent on Oct. 12 to Defense Secretary Harold Brown for forwarding to President Carter, delivered a broadside against what is now the new strategic arms limitation treaty. "These issues require satisfactory and unambiguous resolution before the SALT II negotiations can be considered adequately completed," the memo said. Yet, the JCS now endorse the treaty even though no "resolution" was achieved.

No wonder the administration stonewalls defense-oriented senators who have been demanding this and other JCS memos. While the public voice of the JCS endorses SALT II with some equivocation, the secret voice of JCSM-321-78 is so antagonistic that it would be lethal propaganda against the treaty.

Moreover, statements in the memo directly contradict the chiefs' own testimony before the Senate Armed Services Committee in July. The Gen. David Jones who as JCS chairman signed the memo seems a man apart from the Gen. David Jones who led the pro-SALT JCS testimony.

In that testimony, Jones listed as a "significant" concession Moscow's agreement, apart from the treaty, not to increase production of the Backfire bomber. But the memo warned that failure to include the Backfire problem in the treaty could lead to a Soviet "breakout" -- that is, secret preparation for a major post-treaty military advantage.

"We regret the decision," it said, "not to insist on counting the intercontinentally capable Backfire system within the . . . limit. No Soviet assurances can compensate for the fact that Backfire will remain an effective intercontinental weapon within the total Soviet arsenal for waging nuclear war. Moreover, Backfire production and development provide a significant Soviet breakout potential, an option we would be hard-pressed to match in the near term."

In July, Jones sloughed off suggestions that SALT II leaves the United States with no bargaining position for SALT III. In October, Jones warned that SALT II "will significantly reduce U.S. negotiating leverage for a SALT III outcome."

In July, the chiefs said Moscow would have to destroy strategic weapons to reach SALT II limits. In October, they had painted this picture: "On the Soviet side, many 'reductions' will actually be conversions to strategically significant non-counters (for example, Bison bombers to tankers and SSNs [missile-firing submarines] to SSNs [attack submarines] and SS-20 [missile] deployments will free ICBMs currently committed to PRC [Chinese] targets."

Jones told the senators "there is nothing inconsistent" between the memos they could not read and his testimony, arguing that negotiations had changed things. "Obviously," the general testified, "we were addressing a moving train." But when the demands of JCSM-321-78 are stacked up against the final result of SALT II, the train had not moved far.

Concerning verification, the memo demanded that "national technical means must be augmented, where necessary, by cooperative meansures." It contended that "we should not only preserve our option, but publicly state our intent, to share cruise missile and related technology with our allies as necessary." No more was done to resolve the chiefs' doubts on these issues than on the Backfire.

Similarly, the memo argued, "It is essential that any agreement preserve the U.S. option" for a mobile missile. Yet, the SALT II verification requirements forced a mobile basing mode for the proposed MX that is by no means the chiefs' first choice.

In overall description of arms control, the October generals do not resemble the July generals who saw little danger in the treaty. "Some may conclude," said Jones in October, "that the treaty, by itself, will arrest the very dangerous adverse trends in Soviet strategic forces, including current and projected forces . . . this is simply not the case . . . the focus on constraining what the Soviets could do without a SALT agreement has obscured . . . what they have done, are doing and can do within the SALT framework."

Under SALT I, warned the chiefs, the Soviets have reached "at least parity with U.S. strategic nuclear forces, and the SALT II agreement being negotiated provides neither incentive nor requirement to restrict substantially the pace of their current programs."

JCSM-321-78 eloquently mourned the "recurring theme in U.S. history" of seeking security in treaties. "Despite repeated disappointments on this score throughout the 20th century," it said, the SALT process "contains the seeds of exaggerated expectations and serious public misunderstandings about the adequacy of our strategic position and programs."

Jones did indeed repeat those words in his public statement in July. Unfortunately, the heart of his testimony ignored that timely warning.