Mexico City — The Reagan administration's latest charges of sharply increased Soviet military aid to Cuba underscore Washington's growing resolve to quarantine the Caribbean island as the Western Hemisphere's chief troublemaker.
Despite urgings by Mexico and several other hemisphere governments that the United States seek accommodation with Cuban President Fidel Castro, there apparently is to be no diminution in the hard-line American approach on Cuba.
In fact, according to US officials, some of whom are in Mexico to help plan October's economic summit, the US is likely to step up its anti-Castro approach.
Among measures under study by the administration area reinvigorated trade embargo against the island and possible establishment of a Radio Free cuba based in south Florida and beamed directly at the island.
There is even a hint that President Reagan will, at some early date, speak out forcefully on what the administration views as "Cuban adventurism in the Caribbean and Central America" and outline a series of countermeasures.
US officials feel there is significant support in Latin America for such an approach -- particularly from Colombia, Costa Rica, the Dominican Republic, and Venezuela, as well as from Ecuador and Peru.
This support would counterbalance, in the US view, Mexican opposition to the idea.
But even if it does not get such support, the administration feels obliged to deal harshly with Cuba, US spokesmen say, US officials believe Cuba is the major supplier to leftist guerrillas in El Salvador and Guatemala as well as the equipper of Nicaragua's new Army.
Secretary of State Alexander M. Haig Jr. and other US officials spent much of the weekend outlining to foreign ministers here in Mexico the charge of massive new Soviet aid to Cuba -- and the presumption that some of this is going to Central America.
Earlier Thomas O. Enders, assistant secretary of state for inter-American affairs, stated that there has been an "ominous upswing" in Cuban arms shipments to El Salvador and Nicaragua.
Recent reports of at least 24 Soviet-built T- 55 tanks, allegedly sent to Nicaragua from Cuba, are part of the arsenal of US charges of "Cuban adventurism."
Mr. Haig went before the Senate Armed Services Committee Oct. 30 to outline the US position. He spoke behind closed doors, but released a portion of his remarks.
He said the level of advanced Soviet weaponry now arriving in Cuba may rival the record amount sent in 1962, the year of the Cuban missile crisis.
Other Washington officials charged that enough light weapons reached Cuba in April and May alone to equip a militia force of at least 1 million men.
In addition, Washington indicated over the weekend that the Soviets are also providing new ships for Cuba's Navy. A Koni-class frigate, capable of antisubmarine warfare, was sighted last week in the Mediterranean, headed westward and flying the Cuban flag. Rather than use its own power, it was under tow by an ocean-going tug, perhaps to conserve fuel.
US spokesmen say they are less concerned with such new naval equipment than with the advanced land-based weaponry, but suggest that the new ship has to be seen as part of the total Soviet package to Cuba.
Meanwhile, a war of words between Washington and Havana is under way over Fidel Castro's charge that the the US may have been responsible for unleashing the current wave of dengue fever that Cubans have been suffering from in recent weeks.
"Totally false" and "totally without foundation," US spokesmen say. The State Department also suggested that DR. Castro, in making the charge, was trying to explain away Cuba's "failures and internal problems."
Washington's increasing hard line against Cuba could affect both the limited diplomatic relations and the growing air charter business between Miami and Havana, although State Department spokesmen playing down the possibility.
The two countries maintain relations through interests sections in third-country embassies in each other's capitals, and a US air charter firm in Miami maintains a limited schedule of flights on the 45-minute run between the US mainland and Cuba.