Growing turmoil in Central America and the increasing possibility that one or more states could be taken over by militant anti-American governments pose a vexing challenge for U.S. hemispheric policy.

In Nicaragua, and lesser extents in El Salvador and Guatemala, the United States sees itself caught between the equally unattractive alternatives of repressive government and radical forces who raise the specters of "another Cuba."

The possible impact of a revolutionary takeover in one of these countries extends far beyond the volcanic isthmus itself. State Department domino theorists agonize over the effects of a single fall when the dominos are in the U.S. backyard.

At the same time, Carter administration policy toward Nicaragua's civil war has already separated the United States from the more outspoken positions taken by some of Latin America's most influential countries, especially Mexico. It also has provoked a bitter U.S. domestic debate that threatens the success of the Panama Canal Treaties, as treaty opponents accuse Panama of aiding Nicaraguan revolutionaries.

Here on the battleground, U.S. policy has convinced each side of the struggle that the United States has joined its enemy.

Simply and repeatedly stated, that policy is one of ostensible noninterference in the affairs of the region. It has meant the end of most military aid to three countries whose armed forces traditionally have been trained and armed by the United States.

Overt acts of government repression and massive human rights abuses are regularly denounced by the State Department, although the legitimacy of the military-based governments has not been publicly questioned, except recently in the case of Nicaragua.

In equal measure, guerrilla terrorist acts are condemned and concern is expressed about possible communist advances.

But after so many years of U.S. dominance over their political affairs, and their economies, Central Americans now find it difficult, if not impossible, to believe in U.S. "noninterference."

While Nicaraguan President Anastasio Somoza has accused Carter of trying to overthrow his government, Sandinista guerrillas locked in bloody battle against Somoza say their victory is held back by continued U.S. support for him.

In Guatemala, the U.S. Senate Foreign Relations Committee recently recommended that all assistance be stopped because of continuing repression and assassinations of political and labor leaders. Although the Guatemalan foreign minister quickly flew to Washington to complain and received reassurance of support from Secretary of State Cyrus Vance, his government declined to accept the reassurances and angrily refused all assistance.

Leftist militants in El Salvador, where growing political violence has claimed approximately 75 lives in the past three weeks, march to chants of "Down with Yankee Imperialism."

Yet officers within El Salvador's beleagured military government blame the United States for leading them up a deadend street and abandoning them at what they see as their darkest hour.

"We didn't make the choice" to fight communism, a high-level Salvadoran officer said, "You did. The State Department was supporting us, and now you don't like the way we do things anymore.

"Now you say the military is not equipped to confront economic and social problems. Be sure, we are prepared. But to do it, we have to kill some people. To have a democracy, some people will have to die."

While that kind of reasoning stuns even State Department conservatives, increased polarization and leftist militancy in these countries has made it clear that the officer is not completely out of touch with local reality.

In the middle of the battles within each of the three strife-torn Central American countries is a group of center-left and moderate politicians whose activities in recent decades have been limited to feeble and abortive challenges to the military power structure and armchair discussions.

Recent U.S. attempts to prop up the civilian centrists, particulary in Nicaragua, have run up against the effects of decades of political deep freeze in all three countries. U.S. diplomats attempting to mediate in Nicaragua last fall found that the anti-Somoza moderate politicians they promoted as an alternative government had neither the will nor the mass support, after years of restricted activity, to effectively challenge him.

Even these politicians suffer from the widespread Central American belief that everything that happens here is part of a grand American plan, and largely blame the United States for the mediation collapse.

The U.S. policy question now simply is whether to allow events to take their course in Central America's three hotspots, hoping that something acceptably democratic will emerge when the smoke has cleared, or to go all out to guarantee a result acceptable to the United States.

One of the difficulties in making such a decision is the general similarity, and widely differing details, of situations in Nicaragua, El Salvador and Guatemala.

All three can trace their trouble to economic inequalities, closed political systems and unchecked military power. All have experienced the transformation of the powerful Catholic church from a strong conservative ally to a supporter of forces for moderate change.

All three are victimized in varying degree by leftist guerrillas they say are part of a single Moscow-led conspiracy. All believe the Carter administrations's human rights advocacy has given aid and comfort to their opponents.

Yet the differences are substantial. In Nicaragua, widespread dislike of Somoza is matched by general popular support for the Sandinista guerrillas. There is little doubt that nothing short of Somoza's removal will end the conflict, yet most of the moderate opposition can be expected to then drop out of the struggle.The country is only moderately populated, rich in resources and self-supporting.

In El Salvador, President Carlos Romero is generally considered one of a largely indistinguishable supply of conservative Army generals whose replacement would change little.

Leftist guerrillas appear to have little support from the rest of the population. But military repression against all forms of social protests, motivated by a near fanatical fear of subversion, has made the population radical and served the purposes of a wealthy elite who oppose needed economic change in this vastly over populated country.

Although Guatemala has leftist guerrillas too, they are not major actors. Guatemala's military government and rightist forces use terrorist tactics in an assassination offensive against political, labor and student leaders. The offensive appears to be motivated both by greed and the desire to head off a Nicaragua or El Salvador situation before it can develop there.

Regardless of what policy the United States develops, there seems little question that change will come in Central America. At this point it is unclear whether the United States wants to or is capable of influencing that change. CAPTION: Map, no caption, By Richard Furno - The Washington Post