MOSCOW — The Soviet Union, officially disclosing for the first time its troop strength in Afghanistan, said Thursday that it had 100,300 soldiers there before beginning its military withdrawal May 15.
Western estimates, based largely on U.S. satellite surveillance and radio monitoring, had put the number of Soviet troops in Afghanistan at roughly 115,000, with as many as 40,000 in support positions across the Soviet-Afghan border in Soviet Central Asia.
Moscow had kept secret the extent of its deployment. All through the 8 1/2 years of the war in Afghanistan, Moscow had said only that it had a "limited military contingent" there.
On Thursday, Marshal Sergei F. Akhromeyev, the Soviet chief of staff, disclosed the total and confirmed that 9,500 had left in the past 10 days. He said that "at least an equal number will return home before the end of the month."
Aides to Akhromeyev, who is also the first deputy minister of defense, said they were confident that more than half of the Soviet force would be withdrawn by Aug. 15 under the agreement signed last month by Afghanistan and Pakistan and guaranteed by the Soviet Union and the United States.
The rest are to leave by Feb. 15, although Soviet officials have left open the possibility that some military advisers might remain if requested by the Afghan government.
Akhromeyev's aides said they were not certain, however, that one-fourth of the troops will have withdrawn by the time that the U.S.-Soviet summit meeting begins here Sunday.
"The withdrawal is proceeding more or less on schedule," one senior officer said, "but it is not without complications and difficulties caused by the opposition ( moujahedeen rebel) groups, which are stepping up their attacks. . . . Still, this is something we want to do to improve the atmosphere around the summit, and if we can, we certainly will. We in the armed forces are committed, strongly committed, to the success of the summit."
On Wednesday the Soviet Union published, for the first time, its casualties in the war, the country's longest conflict in modern history. Gen. Alexei D. Lizichev, head of the armed forces' political directorate, said that 13,310 soldiers had been killed and 35,478 wounded, and that 311 were missing in action.
Along with these disclosures has come a debate, still limited but public for the first time, on whether the Soviet Union was right to intervene in Afghanistan in December, 1979, in order to save the embattled Marxist regime there.
Some critics of government policies under Leonid I. Brezhnev, the late Soviet leader, are arguing that the intervention was a major blunder. Soviet officials are taking the ambiguous position that although the intervention was requested by the Kabul government and was legally justified, it was perhaps a policy mistake.