Defense Secretary Caspar W. Weinberger said today that he "disagrees very strongly" with Americans in Congress and elsewhere who, out of frustration about low Japanese defense spending, have called for revision of the U.S.-Japan Treaty of Mutual Cooperation and Security.

The secretary said that while such frustrations are perhaps understandable in some ways, "it is not effective at all to use threats or suggestions that amount to weakening ourselves and our allies by reducing our defense commitments."

Rather, the secretary said, these "unfortunate, isolationist sentiments" need to be countered by pointing out the military and political "facts that require that we the United States and Japan stay together."

There have been a variety of congressional resolutions in the past year that have sought to force Japan into spending more on military preparedness or face, (in some cases) revision of the 30-year-old treaty. That treaty extends American military protection to Japan and gives the United States base rights here.

In addition, recently a committee was formed of more than 100 members of the Japanese legislature who want to alter the treaty to give Japan more leeway to expand militarily and make Japan more of an equal partner.

Weinberger, questioned about these movements in both the U.S. and Japanese legislatures at a press conference today, made clear he did not favor changing the treaty for any reason. He added, however, that the mood among some in Congress to take action against Japan is a very real reflection of how seriously Americans take the concept of burden-sharing among allies. Weinberger said this was why it was so vital to talk to foreign leaders and make them understand how important this emotion was.

Weinberger is here on a three-day visit in which he will try to convince Japan's leadership to do more for the common defense while avoiding controversy in a country where the military budget and missions of the Japanese Self-Defense Force, as the military establishment here is called, have been a politically explosive subject since World War II.

Aside from not wanting any public threats to change the treaty, U.S. officials also do not want it changed because that might set off a lengthy and unpredictable debate in the parliament here that could throw all defense matters into a legislative limbo.

Saturday, Weinberger meets with Prime Minister Zenko Suzuki, and senior aides say he is certain to press the Japanese leader to "substantially increase" defense spending in the five-year defense plan period between 1983 and 1988. These officials say the idea is not to press Suzuki for a specific amount or percent of gross national product for defense but rather to get agreement on the capabilities that Japan needs most and to get them into service quickly.