The Reagan administration is posing two new "test cases" for Soviet-US relations, but an obliging reply from the Kremlin on either isn't likely any time soon, diplomats here suggest.
The Americans want Moscow to move toward withdrawing its estimated 85,000 troops from Afghanistan, and also nudge Soviet-allied Vietnam to yank a much larger troop force from Cambodia.
A UN-sponsored conference on Cambodia, boycotted by the Soviets and their Southeast Asian allies, is getting under way in New York. The US and Western Europe would like negotiations to start on the Afghan issue as well.
But the Soviet position on both crises is, so far, similar: an insistence on international recognition of the Cambodian and Afghan regimes -- which were installed, respectively, with the help of Vietnamese troops in January 1979 and Soviet troops in December of that year.
Soviet policy on either issue could yet change. The men in the Kremlin have shown themselves to be a pragmatic group and, if one judges from private remarks by Soviet officials, they see relations with the US as central to their overall foreign policy.
But the current stormy climate of those relations, diplomats here suspect, may be one reason the Kremlin will rule out any early change on Afghanistan or Cambodia.
The Reagan administration's premise seems to be that if the Kremlin is really as serious as it says about improving superpower ties, then Soviet softening on the two issues would be a good signal.
Soviet officials put things differently.
For them, it is Mr. Reagan who is fouling up the superpower climate. They see him as a man intent on burying the idea of East-West detente, tearing up a painstakingly negotiated SALT II pact, building up US military might, arming Soviet rivals, and lecturing the Kremlin on morals.
Worse, one Soviet analyst argues, Mr. Reagan seems to do much of this with the express aim of forcing this nation's strained economy to cope with a reinvigorated arms race.
"Mr. Reagan wants to put everything in doubt," complains one senior Soviet official privately. "He wants to start everything over. This might be natural for a private individual, but when this individual is president, well, this is dangerous."
While winning little world support for their contention that there was nothing at all wrong with the invasions of Afghanistan and Kampuchea (as they call Cambodia), the Soviets are also beginning to portray both crises as part of the wider international balance of forces.
When Soviet officials gaze southward toward Afghanistan, they see a new US arms deal with neighboring Pakistan.
When they look southeast toward Cambodia, they see signs the US may also sell military equipment to the Soviets' Asian rival, China.
The Cambodia conference is dismissed as part and parcel of Western "anti-Sovietism" in Southeast Asia, and European calls for talks on Afghanistan as part of similar "imperialist" designs in that region.
Above all, both crises seem viewed increasingly here as superpower issues.
Both are costing the Kremlin, whether in lives (Afghanistan), money (Cambodia), or political prestige (both). But diplomats here suggest that these very investments will complicate any eventual softening of Soviet policy on either front.
To the extent that Afghanistan and Cambodia are also seen as "superpower issues," these analysts add, the Soviets would seem likely to fear giving the impression of retreat before President Reagan's tough foreign policy line.
At the very least, diplomats assume that Moscow would want something concrete in return: probably outside acceptance, if not recognition, of the new order in Cambodian and Afghanistan; ideally, some i ndication of fundamentally better treatment from Washington.