Following are excerpts from Mikhail S. Gorbachev's speech today in Vladivostok, as distributed in translation by the Soviet press agency Tass. His remarks have been grouped by subject matter. Afghanistan Having thoroughly assessed the situation that has developed and having held consultations with the Government of the Democratic Republic of Afghanistan, the Soviet leadership has adopted a decision that I am officially announcing today: Six regiments will be returned home from Afghanistan before the end of 1986 - one armored regiment, two motorized rifle regiments and three antiaircraft artillery regiments - with their integral equipment and armaments. These units will be returned to their areas of permanent deployment in the Soviet Union, in such a way that anyone interested can easily verify it.