MOSCOW -- Soviet leader Mikhail Gorbachev Monday announced the withdrawal of six regiments -- about 6,000 troops -- from Afghanistan in a peace gesture made two days before the next round of U.N.-sponsored talks on the war.
But Gorbachev, commenting on President Reagan's reply to the Soviets' latest arms proposals, indicated the 'Star Wars' anti-missile program remained an obstacle in the U.S.-Soviet nuclear arms negotiations in Geneva.
Gorbachev, in a 90-minute nationally televised speech from the Pacific coast city of Vladivostok, said 'the states concerned' were told in advance of the plans to return six Soviet regiments from Afghanistan to their home bases by the end of 1986.
'It must be answered by the curtailment of outside interference in the affairs of the Democratic Republic of Afghanistan,' Gorbachev said.
The six units listed by Gorbachev were one armored regiment, two motorized rifle regiments and three anti-aircraft artillery regiments.
Western military experts said Soviet regiments vary from only about 400 men in artillery regiments, to 1,000 in armored regiments, to 2,000 in motorized rifle regiments. If the regiments are at full strength, the amount of troops involved in Gorbachev's announcement is about 6,000, the experts said.
The Soviet Union, which has an estimated 115,000 troops in Afghanistan, maintains that outside powers -- especially the United States and Pakistan -- are behind the Moslem rebellion aimed at unseating the Soviet-installed government in Kabul. Soviet troops invaded Afghanistan in 1979.
The Afghan government is seeking a Soviet withdrawal in four years, while neighboring Pakistan, which has been flooded by Afghan refugees, wants the Soviets out in 4-6 months.
In Islamabad, Pakistan, Afghan resistance leaders called Gorbachev's announcement a 'diversionary tactic' masking Soviet unwillingness to leave and vowed the 'holy war against the Soviet invaders will continue unabated until the last Russian leaves Afghanistan.'
In Washington, State Department spokesman Bernard Kalb noted similar withdrawals announced in the past 'were part of regular rotations of troops without any decrease in the total number.'
The move to 'speed up political settlement and to give it another impetus' came two days before the resumption of the seventh round of the deadlocked U.N.-mediated Afghan peace talks in Geneva.
'The return of the all Soviet troops from Afghanistan can be sped up,' Gorbachev said. 'Schedules for their stage-by-stage return have been agreed upon with the Afghan side.'
However, Gorbachev warned that 'if the intervention against Afghanistan continues, the Soviet Union will stand up for its neighbor.'
In Islamabad, a Pakistan Foreign Office spokesman called the announcement 'a small first step toward complete withdrawal of Soviet troops from Afghanistan.' He said the timetable is the major unresolved issue in the talks.
But a Western diplomat in Moscow said, 'It's chicken feed. It's a gesture. I think Gorbachev will have to show a good deal more if he is going to convince Western critics.'
The diplomat said the Soviet media has displayed a more self-confident tone about Afghanistan recently and 'they may feel they don't need all the troops.' The diplomat also said it would be impossible to know if total forces were reduced or if the withdrawal was only a routine rotation.
The move on Afghanistan -- one of the regional conflicts dividing the United States and Soviet Union -- was accompanied by Gorbachev's first comment on a letter Reagan sent last Friday.
Gorbachev said Reagan's reply to Soviet arms proposals made in June would be studied with 'responsibility and attention.'
He said he would judge the response on two points: 'The extent to which the proposals contained in the letter meet the principle of equal security, and whether they make it possible to reach effective joint solutions in the field of ending the arms race and preventing its spreading over to outer space.'
Although the exact contents are secret, the Reagan administration has publicly repeated commitment to 'Star Wars,' formally known as the Strategic Defense Initiative.
Gorbachev proposed a one-third cut in offensive nuclear warheads and a 15-year extension of the Anti-Ballistic Missile Treaty. The Soviets say deploying 'Star Wars' would violate the treaty.
The Soviet leader also repeated that he favors a second summit with Reagan, but said it should aim 'for the improvement of the international situation and to speed up the course of talks on the reduction of armaments.'