Pervasive US role in Central America fosters dependency without alleviating social ills. US presence has influenced the lives of Central Americans for decades. US business, troops, and aid have molded the region's economic and political scene, creating resentment that fuels guerrilla movements. Today, billions of dollars flow to area governments, but critics say the aid does little to solve enduring problems.

Sixty years ago, launching his war against United States Marines occupying Nicaragua, Augusto Sandino taunted his enemy: ``More than a battalion of you, blonde invaders, will bite the dust of my wild mountains.'' Last year, the Sandinista government reissued that challenge on a billboard depicting US mercenary Eugene Hasenfus in handcuffs. It is a phrase whose ``anti-Yanqui'' sentiments are echoed in slogans from other revolutionary movements in the region.

``Duarte and the Yanquis out,'' demands the Salvadorean guerrillas' Radio Venceremos.

``The Guatemalan government ... is increasingly an accomplice in the crimes of Yanqui imperialism,'' says the Guatemalan Guerrilla Army of the Poor.

Many decades of heavy US economic, military, and political influence in Central America have provided a focus of resentment, that has helped spawn guerrilla movements. American influence is increasingly felt in the region's growing economic dependence on the US, both in trade and aid.

The heavy US involvement began more than a century ago, through US business interests using plentiful land and labor to grow and export profitable crops in these ``banana republics'' - spuring resentment among poor, landless workers.

Since the Panama Canal was built in 1904-1914, and especially since the 1959 Cuban revolution, however, the region has taken on greater strategic and political importance to Washington. Policymakers, worried about a tide of social unrest lapping at US shores, for years propped up repressive military regimes throughout the region. More recently, they have lavished billions of dollars in economic and military aid on US allies, which has only increased their dependency on Washington.

``If the United States let go of our hands at the moment, we [countries in the region] would sink,'' says a Central American Integration Bank official.

Costa Rica, with 2.7 million people receives $178.3 million annually in US economic aid. Averaging out to $60 per person, this is one of the highest per-capita levels of US aid. El Salvador receives the most US dollars in the region. It is relying this year on $618 million US aid to keep its economy afloat and to fight leftist guerrillas.

While Central American governments depend on money approved by Congress, hundreds of thousands of individuals depend on money sent by relatives living in the US.

Salvadorean emigrants, for example, send home between $600 million and $1 billion a year, according to a recent study. That adds up to $140 a month for each of the families on the receiving end - three times as much as an unskilled laborer earns in El Salvador.

Much official US aid, critics contend, has done more to prop up unbalanced economies and finance the import of expensive US goods than to ameliorate social conditions.

``How sad it is that hungry countries have become forced buyers of goods from the highly developed countries,'' laments H'ector Marroquin Arevalo, Dean of Agricultural Studies at El Salvador's National University.

Every country in the region except Nicaragua - subject to a US trade embargo since May 1985 - has seen its trade dependency on the US increase in recent years.

While business with the rest of the world dropped off from 1979 to 1984, regional exports (excluding Nicaragua's) to the US and Canada rose from 39 percent of the total to 45 percent. Imports from North America climbed from 35 percent of purchases to 42 percent over the same period.

The Sandinistas, meanwhile, are now dependent on East-bloc allies for more than 50 percent of their imports.

While high levels of US political, cultural, and economic dominance in the region have prompted some to take up arms, they have led more moderate voices to call for new international markets and more intra-regional trade.

As part of Central America's new peace process, the region's economy ministers have been meeting to plan joint economic initiatives and closer cooperation. These moves recall the old dream of a Central American Common Market, a scheme born in the 1960s that never really got off the ground because of mutual mistrust and disagreements over exchange rate policy.

``But the common market is more asleep than dead,'' says one Western diplomat. ``It did demonstrate that it is possible to facilitate trade between Central American countries.''

But few planners see regional self sufficiency as the whole answer. The countries involved are too poor and too deeply in debt not to seek bigger and more lucrative markets for their exports. ``The truth is Central America cannot base its future economic and social development on this [regional] market'' alone, Costa Rican President Oscar Arias S'anchez has said.

``We will have to be more efficient to penetrate other markets. But one important barrier that will have to be overcome is protectionism'' in the developed countries, President Arias adds.

Another problem, which Central America shares with all third-world nations, is a slump in commodity prices. Terms of trade fell in the region by almost 50 percent from 1978 to 1985: A farmer had to sell twice as much coffee, or cotton, to buy the same imported tractor.

At the same time, the wars in Central America have stifled both local and foreign investment. In El Salvador, says one European diplomat there, ``the very fact that the guerrillas have the economy as their central target is a big disincentive for investment. It kills confidence.'' Peace, he adds, ``would give a breathing space'' to the region's economies.

For Mr. Arias, peace and development are inextricable. ``There will be no real peace without democracy. And without peace, it is not possible to achieve economic and social development,'' he said

Second in a three-part series on the roots of conflict in Central America.