Defense Secretary Donald H. Rumsfeld, delivering the Pentagon's annual posture statement, made the outgoing administration's case yesterday for keeping military spending high for at least the next five years.

He warned the unless a new block-buster ICBM, strategic bombers and a fleet of warships were built, the Soviet Union would get so far ahead militarily that the United States would lose influence around the world.

President-elect Jimmy Carter and his Defense Secretary, Harold Brown, thus will be up against a Pentagon brief of 353 pages if they try to downplay the Soviet threat and make cuts in the Pentagon budget as promised during the presidential campaign.

In contrast to the "buying only what we need" guidance laid down in 1961 when Brown started his first tour at the Petagon, Rumsfeld argued yesterday that "the United States effort must be as serious, as steady and as sustained as that of the Soviet Union."

He projected Pentagon budgets going from $123.1 billion in the next fiscal year, 1978, to $166.8 billion in 1982. Although the United States and the Soviet Union have "rough equivalency" today in strategic forces, Rumsfeld said, that much money will be required in the future to maintain the balance.

The departing, Defense Secretary also firmly embraced the strategy of his immediate predecessor, James R. Schlesinger, by arguing in the posture statement that the United States must prepare to fight a limited nuclear war as well as deter an all-out one.

Rumsfeld said Soviet leaders do not share the American view that nuclear war would be so mutually destructive that actually waging one would be unthinkable.

In one passage illustrative of the rough rhetoric he chose for his farewell statement on national defense, Rumsfeld said the Russians "must be accepted for what they are, not for what we want them to be. Their actions indicate that they take nuclear war seriously. The United States must do so less."

In that context, Rumsfeld said the United States must deploy nuclear weapons so controlled and targeted that the President would have "at least the option to respond in a deliberate and controlled fashion."

Critics have long argued that limited nuclear war is illusory because neither side would restrain itself once the first nuclear weapon was fired.

At the other end of the nuclear war spectrum, Rumsfeld said that destroying Soviet cities in retaliation for an attack on the United States might not be enough. "An important objective of the assured retaliation mission," he said, "should be to retard significantly the ability fo the U.S.S.R. to recover from a nuclear exchange and regain the status of 20th century military and industrial power more rapidly than the United States."

This is "a new goal" for retaliation that should not have been set, Herbert Scoville Jr., former CIA deputy director, said at an Arms Control Association luncheon meeting called yesterday to assess the posture statement. He said the Ford administration is overreacting to the Soviet military buildup and "poor-mouthing" U.S. strength.

In making the case for building a new family of an maintaining armed forces numbering 2.1 million people in peacetime, weapons Rumsfeld said: "Our nation simply cannot allow Soviet capabilities to continue expanding and U.S. capabilities to retrench - as they have over the past decade - without inviting an imbalance and, ultimately, a major crisis."

Not only must the United States advance into a new generation of super-weapons for nuclear war, the secretary said, but must continue to improve the conventional forces that are the best insurance against the need to use nuclear weapons.

Because Soviet ocean-spanning missiles are getting more accurate all the time, Rumsfeld said, U.S. land-based Minuteman ICBMs are becoming increasing vulnerable to a surprise attack. Therefore, he argued, it is time to speed up the development of the MX blockbuster ICBM, which could be moved from place to place around a missile field, making it harder to target and hit.

Deploying the MX, Rumsfeld said, "might serve as an incentive to the Soviets to slow their momentum in deploying new ICBMs and seek mutual reductions in strategic offensive force levels."

Rumsfeld is recommending to Carter that $294 million be spend on the MX in the next fiscal year so it could be deployed in the "the mid-1980s."

The B-1 bomber is also needed to maintain "strategic equivalance," Rumsfeld said, and is "the most cost-effective alternative for carrying out the bomber force mission."

Carter said during the political campaign that putting the B-1 into production would be "wasteful." Brown, when he was director of Pentagon research, started the studies that led to the B-1 after the B-70 bomber program was canceled.

In a decision that will be hotly contested in Congress, Rumsfeld said he had scrapped the plan to build a fourth Nimitz class aircraft carrier costing about $2 billion because a new National Security Council study had concluded that the better course was building more but cheaper carriers.

Instead, the plan Carter will inherit calls for starting a new class of smaller carriers that would be used by aircraft that could take off and land on a short stretch of deck.

Rumsfeld also said outer space could become a new battleground and recommended a number of programs to protect American communications and reconnaissance satellites.

Stating "no evidence is available that the Soviet leadership intend to launch a direct military attack on the West in the immediate future," Rumsfeld said "the darker face presented by the Soviet Union" requires U.S. defense budgets of these amounts in the future:

Fiscal 1978 $123.1 billion

Fiscal 1979 $135.4 billion

Fiscal 1980 $145.8 billion

Fiscal 1981 $156.7 billion

Fiscal 1982 $166.8 billion.