The NATO alliance's inability to agree on where to base new U.S. medium-range nuclear missiles has set back until mid-1963, at the earliest, deemployment of the weapons to Europe, according to previously secret congressional testimony released last week.

The 1,500-mile, ground-launched cruise missile (GLCM), which could reach the Soviet Union from any country in Western Europe, may not be available before 1984, Pentagon sources said yesterday, if NATO ministers fail to approve a basing plan at their major meeting planned for December.

The GLCM and an extended-range version of the Pershing II mobile missile, also in final development, are designed to cunter Soviet introduction wthin the past two years of the SS20, a 2,00-mile mobile ballistic missile that carried three warheads.

Among the issues that remain to be resolved are how many missiles will be deployed; what the mix will be between the extended Pershing, with a 1,000-mile range, and the GLCM; and whether they will be controlled solely by U.S. forces or under a "two-key" system where the basing country has an equal role in firing.

At a closed hearing in April, Air Force officials said their program called for buildng 696 GLCM's at a total cost of $1.7 billion.

Since NATO has yet to agree on just how many missiles will be deployed to Europe, Lt. Gen. Thomas Stafford, Air Force deputy chief of staff for research and development, said, "There is a possibility that we could reduce that number by approximately 25 percent.

The protocol to the new strategic arms limitation treaty prohibits the United States from deploying the GLCM with a range greater than 360 miles before December 31, 1981. That language could have held up in the 1,500-mile GLCM program had not problems already developed within the allinance over basing.

The GLCM program got its Pentagon go-ahead for advanced research and design in October 1977. In the normal course of things, first deployment could have been made in 1981.

At the April hearing, Stafford said that if the protocol limitation were continued, "we would seriously consider the need for this weapon system."

Pentagon sources said yestersay that the weapon at less than 1,500 miles would not be worth the funds being spent on it. But they said they did not expect the protocol limitations to be in effect after 1981.

At present, the Pershing I, which can be fired 400 miles, is the longest range land-based missile system in the NAT0 arsenal. Placed in West Germany it cannot threaten targets in the Soviet Union.

Though the NATO allies are concerned that the SS20 and older Soviet medium-range missiles give that country a large advantage over NATO in such longer range nuclear weapons, the alliance countries have hesitated to agree to base the new missile on their soil. CAPTION: Picture, Sen. Jackson displays models of U.S. (white) and Soviet (black) missiles at hearing. By James K. W. Atherton -- The Washington Post