Soviets Switch Stance, Admit Treaty Violation : Arms Control: Shevardnadze calls a huge radar station in Siberia a blunder. He also decries the Afghan invasion as beyond ‘the norms of proper behavior.’

Foreign Minister Eduard A. Shevardnadze, reversing years of denials, admitted Monday that the Soviet Union had violated a key arms control treaty with the United States by building a huge radar complex in Siberia.

Construction of the station, begun a decade ago and now about to be dismantled, was a strategic blunder, Shevardnadze told the Supreme Soviet, the country’s Parliament, for it had jeopardized the 1972 Soviet-American treaty limiting anti-ballistic missile defenses and had made Washington wary of signing further arms control agreements with Moscow.

“All these years, we have been fighting for the preservation of the anti-ballistic missile treaty as the basis for strategic stability,” he said. “Yet, at the same time, the construction of this station, as big as an Egyptian pyramid, directly and openly violated the ABM treaty.”

Shevardnadze informed Secretary of State James A. Baker III at their meeting a month ago at Jackson Hole, Wyo., that Moscow intended to dismantle the station at Krasnoyarsk completely to ensure compliance with the ABM treaty.

In a strikingly candid public review of Soviet foreign policy for the lawmakers, Shevardnadze also denounced the country’s nine-year military intervention in Afghanistan, criticizing it as “violating the norms of proper behavior and disregarding the values common to all mankind.”

Although he was an alternate member of the Communist Party’s ruling Politburo at that time along with Mikhail S. Gorbachev, now the Soviet president, Shevardnadze said they both learned of their country’s invasion of Afghanistan in December, 1979, from radio and press reports.

“We committed the most serious violations of our laws, our party and public norms,” Shevardnadze said in the sharpest criticism yet by a top Soviet official of the country’s decade in Afghanistan. “The decision that led to such grievous consequences for our country had been taken behind the back of the party and the people, presenting them with a fait accompli. “

Surveying international affairs, the Soviet foreign minister acknowledged that political, economic and social turmoil was bringing “historic, qualitative changes” to some of Moscow’s allies in Eastern Europe and that the very speed was causing “some problems and difficulties, but no crises,” in their relations.

The relations were established on the basis of sovereign equality and the right of every country to an absolute freedom of choice, Shevardnadze said. Alluding to the new, non-Communist government in Poland and Hungary’s adoption of a multi-party political system, he said that “the emergence of new political forces does not mean these states are no longer neighbors, allies and friends.”

“One cannot act on the basis of old structures formed in the past,” he said, echoing recent calls here for a review of the future of both the Warsaw Pact and the Council for Mutual Economic Assistance, the socialist trading bloc known as Comecon.

For Shevardnadze, who was delivering the first such foreign policy report to the Supreme Soviet in more than 50 years, the construction of the Krasnoyarsk radar station was virtually a case study on the need for openness and for legislative involvement in decisions on foreign policy and defense.

“Perestroika itself will not save us from mistakes,” Shevardnadze said, referring to Gorbachev’s reform program. “It is very important not to hide them, but to admit and correct them.”

Shevardnadze implied that the Soviet military had misled the country’s civilian leaders on the capability and purpose of the radar station near Krasnoyarsk, causing them to reject U.S. complaints that it violated the treaty.

“It took some time for the leadership of the country to get acquainted with the whole truth and the whole history about the station,” Shevardnadze said, noting that the first U.S. complaints were made more than four years ago. “Finally, we understood that the installation had been built at the wrong place. . . .”

When the Soviet leadership decided to dismantle the station--after first trying to persuade the United States that it was really for space-tracking and intended for scientific research and then turning it over to the Soviet Academy of Sciences--there were complaints, apparently from the military, that Soviet interests were being forgotten, Shevardnadze said.

“Actually, we are saving the ABM treaty, opening the way to the conclusion of the strategic arms agreement and getting both the legal and moral right to insist on a clear answer about American stations in Greenland and England that are being modernized in violation of the treaty,” he added.

In Washington, a senior State Department official described Shevardnadze’s admission as “encouraging,” He said the statement demonstrated that Moscow is “serious” about arms control.

“It says something about the Soviet mind set that is encouraging,” the official said. “The straighter they can be about issues of this sort, the greater the degree of confidence.”

The ABM treaty limits the size and character of anti-missile defenses with the intention of preventing either country from acquiring a defense for all of its territory and thus gaining the confidence to launch a nuclear attack.

The treaty permits the two countries to establish large, phased-array radar stations only along their borders and facing outward to ensure that they are used only for early warning and not for battle management in a defense against incoming missiles.

The Krasnoyarsk station, which was never finished or put into operation, is more than 465 miles from the nearest border--that with Mongolia--and looks out over 2,500 miles of Soviet territory, including fields of intercontinental ballistic missiles. This makes it suited, in the American view, to the management of an anti-ballistic missile defense.

“We should have become interested in who made the decision about the construction of Krasnoyarsk, about the spending of millions and millions of rubles, and more money will be needed for dismantling it,” Shevardnadze said. “All over again, we are made aware that ill-considered decisions cost much.”

Times staff writer Norman Kempster, in Washington, contributed to this report.

CRIPPLED--Strikes and blockades endanger the Soviet economy. A5