Moscow seems to be girding for a superpower test of strength over an Iran minus Ayatollah Ruhollah Khomeini.
Remarks by Moscow officials to diplomats here, and recent official news media coverage, leave little doubt the Soviets expect a United States bid for renewed influence in Iran once the Ayatollah departs. The Soviets see this as a potential threat to their own security interests, officials suggest privately, and are determined to prevent this.
Their minimum hope for developments within Iran is the emergence of a regime that values good relations with the Kremlin.
Diplomats here maintain that the intensity of superpower competition over a post-Khomeini Iran, and the extent to which the Kremlin will be ready to travel in defense of its own policy priorities there, depend in large part on imponderables.
Among them are whether a secular aya-tollah named Leonid Brezhnev survives his Iranian counterpart, the state of US-Soviet relations at the time of Khomeini's passing, and the political situation inside Iran.
In the interim, the Soviets have been balancing a drive for better relations with the present regime by, in effect, serving notice of various rules Moscow feels central to relations with Khomeini's successors.
While more than a few Kremlinologists wonder out loud about matters of transition-in-Moscow, more than a few Soviets seem to suspect a transition south of their border is not too far distant. The Soviet media have long sought to avoid overly close identification with the Khomeini regime. Recent dispatches take this further, speaking of the ''present'' or ''existing'' leadership there with the clear implication it may not be around much longer.
A March 7 dispatch from the Soviet news agency Tass included a particularly equivocal reference to the challenge antiregime militants pose to the Tehran leadership: It termed them ''members of organizations that have taken the path of armed struggle against the present regime.''
Meanwhile, the Soviets have unsheathed a carrot and a stick in a pair of lengthy commentaries on ties with the Tehran regime.