The United States should build a new nuclear arsenal of short-range weapons for Europe to offset the firepower NATO would lose under the Intermediate-Range Nuclear Forces (INF) Treaty, Gen. John R. Galvin, Supreme Allied Commander for Europe, said yesterday.

The four-star Army general, at a breakfast session with defense correspondents, said he supports the INF pact because "as I look at what's left, I come to the conclusion that I can carry out the mission of deterrence and defense. . . . "

But he said INF, which calls for removal of Soviet and U.S. land-based missiles with ranges from 310 to 3,410 miles, carries "more risk than we ought to be ready to take" unless it is offset by upgrading NATO's nuclear and conventional arsenals. Galvin's support of INF is expected to be influential in the Senate hearings on the arms pact, which start next week. His precedessor, retired general Bernard W. Rogers, in his testimony, is expected to be more critical of the treaty. Signed by President Reagan and Soviet leader Mikhail Gorbachev in Washington last month, the pact must pass the Senate by a two-thirds vote to go into effect.

Galvin warned against heeding the warning of Soviet Foreign Minister Eduard Shevardnadze who said in Bonn on Wednesday that introducing new short-range nuclear weapons into Europe would scuttle progress in arms control. Galvin said the Soviets "have taken moves" in that direction but declined to specify what they were.

The general said that to fill the range zone of 310 miles not covered by the INF treaty, the United States and its allies should develop and field a nuclear-tipped successor to the Lance ground-based battlefield missile, and a standoff nuclear missile small enough to be launched by fighter planes; raise the current ceiling of 1,000 rounds on nuclear artillery "because that makes the whole defensive setup less vulnerable," and modernize existing nuclear bombs.

In conventional arms, Galvin recommended that NATO continue to modernize forces while developing new weapons, such as the Air Force's Joint Surveillance and Target Attack Radar System (Joint Stars) for pinpointing tanks on the move, to combat the second and third waves of a Warsaw Pact invading force.

Galvin said he and other NATO leaders may have to set priorities, delay some weapons and even reexamine strategy if money is scarce in an era of declining NATO budgets. He added that NATO and Warsaw Pact force reductions could save money, and implied he favors deep cuts.

"If you go back and look at the recent history of arms negotiations before World War I, before World War II, the big problem was we couldn't bring ourselves to actually make a deep cut. That's what wrecked arms-control negotiations all along," he said.

Galvin agreed with Sen. Carl Levin (D-Mich.), chairman of the Senate Armed Services Committee's conventional forces subcommittee, that assessing the balance requires more than a "bean count" of each side's weapons.

"From the bean count," Galvin said, "it has to go to capabilities; the capabilities to get a warning, to mobilize, to deploy, to reinforce, to sustain, to maneuver, firepower. . . . There's some other countries in the world besides NATO. What are they going to do? And there's geography, industrial capabilities of nations. . . . "

U.S. and Soviet military leaders should tell each other what military forces they fear the most to help guide civilian leaders trying to negotiate mutual reductions in conventional arms, he said.

The general appeared to favor deep cuts in conventional forces of both sides, although he did not say so directly. "We have to be flexible enough to consider what it is that the Soviets think we look like if we're going to convince them what we think they look like," Galvin said. "There's going to be some give and take -- there would have to be."

If the United States does enter into such negotiations, Galvin cautioned, the delegates should remember that that the Soviet military machine "hasn't changed at all" under Gorbachev.