A defense bill in the Senate just before the Fourth of July recess has brought to light a secret Air Force report that the United States has fallen behind the Soviet Union in strategic power with no prospect of catching up.

The admission that parity with Moscow had been lost, perhaps irretrievably, during the first three years of the Carter administration was made in late February in closed-door testimony to Congress by Gen. Richard H. Ellis, commander of the Strategic Air Command: "An adverse imbalance has developed and will continue for several years to come," said Ellis in testimony labeled "secret."

This acount of dramatic Soviet arms progress amid U.S. "cancellations and slippages" constitutes an indictment of Carter defense policy. "If we have learned any lesson," Ellis declared, "it should be that the Soviets have not reciprocated U.S. restraint in any portion of their military power -- conventional or nuclear."

Ellis' shocker compares with the revelation in 1935 that Britain had lost air parity with Germany, but his words have had slight distribution outside defense circles. Although a few members of Congress occasionally mention loss of strategic parity, nobody of stature has hammered home the reality as Winston Churchill did from the back bench 45 years ago.

The general's testimony was cited on June 27 by Sen. Gordon Humphrey, a freshman Republican from New Hampshire, in a letter to colleagues pushing his proposal to deploy $1,000 stockpilled Minuteman III intercontinental missiles. Humphrey cited "press reports" that the SAC commander "testified recently that, since 1977, the United States has lost strategic 'essential equivalence' with the Soviet Union."

The only apparent press report was in the Feb. 22 edition of Defense/Space Business Daily, which reported Ellis' disclosure of the sophisticated Air Force computer study. We obtained a full copy of Ellis' testimony from defense sources.

Ellis cited "a clear and unambiguous" goal for U.S. defense policy set in 1978 by Defense Secretary Harold Brown: "The maintenance of an overall military balance with the Soviet Union no less favorable than the one that now exists." Brown said that "a rough strategic nuclear equilibrium exists between the two superpowers" and pledged to continue it.

The air Force computer studies revealed by Ellis did show equivalence in 1977. "In the short two-and-one-half years since then, the balance of strategic nuclear has shifted," the general declared. The Soviet Union has taken the lead thanks to "changes in the rate of Soviet modernization, compounded with cancellations and slippages of major U.S. programs."

Just to make clear Congress got the message, the SAC commander concluded: "I hope the preceding statement has conveyed an urgent and convincing message -- our current and near-term strategic forces, while capable and ready, are unable to achieve the relative balance possessed just two years ago."

The clarity of Ellis' warning contrasts with the usual from Secretary Brown and members of the Joint Chiefs of Staff. Gen. David Jones, the JCS chairman, in his recent reconfirmation hearings declared that the United States has "moved from strategic superiority to the verge of strategic inferiority." The computer studies, showing inferiority well beyond the "verge," condemn Jones as Pollyanna.

Ellis' testimony also strayed from the Carter party line on remedies. While asserting that the MX mobile missile system is "this nation's top military priority" for the long run, he pleaded for a penetrating bomber in the short run. The B1, scrapped by President Carter, was called by Ellis "the finest strategic penetrator in the world today."

Ellis and other senior officers at SAC are believed privately to favor deploying 1,000 Minuteman III missiles, which was adopted by the Senate before the recess over administration protests. While defense experts might disagree about its military effectiveness, this move is at least a positive message to the Kremlin.

Demonstrations of resolve are needed now, before the loss of strategic parity wrecks the Western alliance. Gen. Jones, who had so often ruled out a Soviet attack, admitted under prodding in his reconfirmation hearings that Moscow "will try to intimidate us or our allies" under the new balance of power.

The question is not only how to remedy this weakness but to find out how it happened. "I am astounded at the indifference with which the press and public seem to view the fact that the government have been utterly wrong about the German air strength," said Churchill in 1935, adding: "We can never catch up." Gordon Humphrey is no Churchill, but he posed the parallel June 27. "U.S. intelligence has grossly underestimated" the Soviet threat, he said, adding: "We may never be able to regain parity."