The Soviet Union celebrated its 71st anniversary Monday with a traditional display of military might on Red Square, and the top U.S. diplomat attended for the first time since the Soviets intervened in Afghanistan.

The parade commemorating the Bolshevik Revolution took on less of a political character than in the past. Defense Minister Dmitri T. Yazov criticized Western defense policies in a short and comparatively mild speech, and banners displayed on the square had an almost exclusively domestic, economic character.President Mikhail Gorbachev and Premier Nikolai Ryzhkov walked onto Lenin's Mausoleum and acknowledged the applause of the crowd alone at the center of the reviewing stand. In contrast to previous years, the other members of the Communist Party's ruling Politburo followed far behind them.

Moscow party leader Lev N. Zaikov stood on Gorbachev's right throughout the parade, a possible indication that he has moved up in the party leadership.

Yegor Ligachev, a conservative who formerly was regarded as the No. 2 Kremlin leader, stood next to Ryzhkov, an indication he has fallen in the hierarchy.

All 11 Moscow-based members of the Politburo attended the gathering marking the anniversary of the seizure of power by the Bolsheviks in 1917. The annual event is often one of the clearest indicators of changes in the hierarchy.

Some of the Soviet Union's most sophisticated military technology, including SS-21 surface-to-surface missiles, T-72 tanks, anti-aircraft weapons, armored personnel carriers and rocket launchers followed. Western diplomats said there were no new weapons.

Thousands of soldiers, diplomats and spectators jammed Moscow's main square under blustery, leaden skies. A light snow fell, the temperature was just below freezing and Red Square was adorned with a giant red-and-white portrait of Lenin and political slogans.

John M. Joyce, the U.S. charge d'affaires, was at the parade, said embassy spokesman Richard Gilbert. It was the first time the top U.S. diplomat in Moscow attended the Revolution Day parade since the Soviets sent soldiers to Afghanistan in December 1979. Gilbert said U.S. Ambassador Jack F. Matlock was out of town.

Ambassadors of other NATO countries also attended.