A statement issued by the military command said the armed forces would fight with the same determination as before, in coordination with "friends and allies", until security and stability were restored "to every inch of national territory".
It said the decision to reduce Russia's military presence was a natural move and was jointly taken by the military leaderships of both countries "after the halt of combat operations on some fronts" in Syria, Reuters reported.
President Vladimir Putin announced out of the blue on Monday that "the main part" of Russian armed forces in Syria would start to withdraw, telling his diplomats to step up the push for peace as UN-mediated talks resumed on ending the five-year-old war.
Damascus rejected any suggestion of a rift with Moscow, saying Syrian President Bashar al-Assad had agreed on the "reduction" of Russian forces in a telephone call with Putin.