Greece intends to adopt a new defense policy next month geared to the belief that the country's main military threat comes from Turkey, not the Warsaw Pact, a spokesman for the Socialist government said today.

Military observers said the move had considerable political shock value but was unlikely to produce dramatic changes in the disposition of Greece's 185,000 troops, which traditionally have been deployed with the historic antagonist Turkey in mind.

Political analysts interpreted the move by Prime Minister Andreas Papandreou as an attempt to deflect radical left-wing criticism in anticipation of a possible U.S.-backed settlement of the Cyprus issue, a major bone of contention between Greece and Turkey. The two countries are members of the North Atlantic Treaty Organization and their differences constitute a threat to its southeastern flank.

Papandreou launched the plan to embrace a "new defense dogma" in a speech Saturday to Socialist Party cadres, but the statement was excised from an official text. Nevertheless, progovernment newspapers focused on the issue today after an apparent nudge from Papandreou, who also is defense minister.

A government spokesman, confirming the newspaper reports, said, "The dogma until today has been that the danger is from the north. We say it is from the east." He added that the government will submit the modified defense plans to the Council for External Affairs and Defense, an interministerial body with final ratification power on policy decisions, in January for approval.

"The conviction that Turkey is the main threat has been stated repeatedly by Papandreou since he came to power," noted a western diplomat. "And in any case the main thrust of the Greek forces has always been concentrated in Thrace and the eastern Aegean islands, which are the border regions with Turkey." [A State Department official said he could not comment because Papandreou's statement was not yet available to him.]

Another western analyst said, "At least some of the Greek troops stationed in the north are supposed to be there for Bulgaria. But who's to know which way they're pointing? It's not clear what military redeployment the new Greek 'dogma' could entail. So far in NATO, the Greeks have followed the alliance precepts," he said.

Greece, with four Army corps, deploys its 2nd, 3rd and 4th Corps, the bulk of its land forces, in the north, center and northeast, adjacent to the borders with Yugoslavia, Bulgaria and Turkey.

The prevailing view seemed to be that Papandreou's motivations were more likely to have been political than military. The move, which normally could be expected to drive yet another nail into the coffin of Greek-Turkish relations, comes at a time of possible improvement in the Cyprus problem that most divides them.

The strategic east Mediterranean island has been split since 1974, when Turkey occupied more than one-third of its territory in response to a coup in Nicosia engineered by the Greek military that was then ruling in Athens.

A current U.N. initiative to reunify Cyprus has been actively backed by Washington, in the hope of also reconciling Greece and Turkey and thus consolidating NATO's southern flank.

Last week, U.N. Secretary General Javier Perez de Cuellar arranged a meeting Jan. 17 in New York between Cypriot President Spyros Kyprianou, of the island's majority Greek community, and Turkish Cypriot leader Rauf Denktash.

Kyprianou said the meeting offers the first "ground for cautious optimism since 1974." The initiative came after a series of concessions by the Turkish Cypriot side on the sharing of both territory and constitutional power in a future federal state.

Greece has said it fully supports Kyprianou's decision to go to a summit. But a Cyprus solution could be double-edged for Papandreou, who has ruled against compromise. The Socialists, like conservative administrations before them, have found the emotive Cyprus issue a useful vote-getter.

To the added embarrassment of the fervently anti-American Papandreou administration, the Greek press has given much play to reports, confirmed by U.S. and Greek Cypriot officials, that Denktash was persuaded to relax his demands after a "direct communication" from President Reagan to Turkey's president, Gen. Kenan Evren, urging concessions on Cyprus for the sake of easing tensions in NATO.

The Papandreou government is now thought to be anxious to deflect resulting criticism from hard-liners in the Socialist ranks, and the pro-Moscow Communist opposition that is strong in the Greek labor movement.

The Communist Party's newspaper delivered a strong attack on the government today under the banner headline, "Reagan Demands a Package Deal," for allegedly being ready to accept a wholesale solution imposed by Washington in the Aegean and Cyprus in exchange for U.S. pressure on Ankara.

[A U.S. source in Washington denied any U.S. initiative while acknowledging active support of the U.N. effort.]

The notion of a "package settlement" has been a recurring one in the Greek press, both left-wing and conservative, in the past week. It has been linked with speculation that Papandreou might opt for early national elections in the spring should he settle longstanding national disputes with Turkey. His terms ends next October.