BRUSSELS, JULY 30 -- The new allied military commander in Europe, Gen. John R. Galvin, said yesterday he is confident that NATO defense strategy will not be jeopardized if the United States and the Soviet Union carry out a proposed agreement to scrap intermediate-range nuclear missiles in Europe and Asia.

Galvin, who succeeds Gen. Bernard W. Rogers, took a more sanguine view of the potential accord than his predecessor by emphasizing that the threat to Western Europe posed by Soviet SS20s and other missiles in the medium-range and short-range category would be considerably reduced.

But he said that the allies should take "compensatory measures" to fill the void left by the elimination of Pershing 2 and cruise missiles under such an agreement.

Before leaving his command, Rogers harshly criticized the so-called "double zero" agreement and suggested that the Reagan administration had been stampeded into accepting the deal.

He was retired at White House orders after voicing grave reservations over the U.S.-Soviet proposals that emerged at the 1986 Reykjavik summit.

"There is no reluctance on my part in accepting the changes in the nuclear face-off in Europe," Galvin said. "NATO's strategy of flexible response will still be valid; however, the means to implement NATO strategy will require buttressing. Otherwise there will be a higher risk than we in the West should accept."

But like Rogers, he insisted that the scrapping of U.S. nuclear missiles as a result of such an accord should lead the allies to deploy newer land-based short-range Lance nuclear missiles, a new long-range air-launched standoff missile and modernization of nuclear-capable NATO aircraft to enable them to penetrate improved Soviet air defenses. Some of these recommendations have already been endorsed by NATO governments.