Moscow has printed its most direct threat of possible military intervention in Poland since the imposition of martial law there a month ago.
The Soviet Defense Ministry newspaper Red Star suggested Jan. 14 that a US-led ''hostile campaign'' against Poland could trigger such a move.
Diplomats here are convinced that Soviet military intervention remains very unlikely. But the Red Star commentary, of an ilk not seen here since martial law was announced Dec. 13, is seen as an acknowledgment by the Soviets that their ''Polish crisis'' is alive and kicking despite the crackdown next door.
A lengthy ''statement'' on the Polish situation Jan. 13 from the official Soviet news agency, Tass, seemed to suggest much the same thing.
Official Soviet reports have indicated that the situation inside Poland is calmer and healthier than before martial law - but that a reliable, long-term solution to the country's economic and political problems remains distant.
Meanwhile, complications in Soviet relations with the West as a result of the crisis in Poland have been worsening since martial law was announced. Thus, Tass marked one month of martial law with a public appeal to the West for international business as usual. (The message of the Jan. 13 commentary was reminiscent of a speech by President Leonid Brezhnev last April, much earlier in the Polish crisis.)
And thus, Red Star has raised anew the possibility of a joint Warsaw Pact ''defense of the socialist gains'' of Poland (reminiscent of a number of Soviet statements before Polish martial law).
Presumably, Soviet officials had hoped that the Warsaw crackdown would allow them to file away such scripts for some time -- as they did, for instance, after defending Czechoslovakia's socialist gains with Warsaw Pact tanks in 1968.
Presumably, too, the hope remains. Time plods on. The West has issues besides Poland to worry about (Western economies, for instance, or the open-ended crisis if the Middle East).
Yet at the one-month mark, the Western reaction to martial law in Poland seems genuinely to have surprised, and unsettled, Moscow. After all, the Soviets did not invade. (They knew, and still know, that option could cost dearly.) Poles cracked down on Poles.
But the US imposed new trade sanctions on Moscow and is mumbling about the possibility of further ones. The West Europeans pledged not to undermine such moves. And some West Europeans, at a NATO meeting Jan. 11, even said they would consider sanctions of their own should the current situation in Poland persist. (Western Europe, by Soviet calculations, is supposed to be yelling at Ronald Reagan to calm down over Poland, and pressing him for early concessions at the arms-control table.)
Against this background, the Tass commentary Jan. 13 in effect told the West Europeans that they should know better than to raise a big fuss over Poland. There are more important issues, Tass said, like arms control.
And Red Star (whether for Westerners or for Soviet soldiers, it was unclear) suggested that the West might be playing with fire in Poland.
The newspaper charged that the West, headed by the Reagan administration, was trying to undermine socialist Poland and interfere in its affairs. ''This, of course, cannot leave indifferent any of the Poland's friends and allies, all [of whom] who are interested in the preservation of its socialist gains.''
''Preservation of socialist gains'' is what Moscow calls the participation of its troops against unrest in East Germany (1953) and Hungary (1956), and against reform in Czechoslovakia (1968).
Red Star said the Warsaw Pact armed forces had at their disposal all the necessary tools for future ''defense of the gains of its peoples.''
To those who would challenge these gains, Red Star said, ''memorable lessons were taught when the issue arose of defending socialism in the GDR [East Germany ], Hungary, and Czechoslovakia.''