For 58 years, the U.S. Navy has practiced everything from airstrikes to amphibious invasions on the Puerto Rican island of Vieques. Now it is engaged in maneuvers of a different sort, launching a political counterattack against Puerto Rican officials who seemed to have won President Clinton's sympathy for demands to end the target practice.

Puerto Rican leaders have complained that live ammunition training on Vieques poses unacceptable economic and environmental costs to the island's 9,300 residents. In response, the Pentagon has lent quiet but potent backing to a proposal to close the huge Roosevelt Roads Naval Station in Puerto Rico--and eliminate the thousands of jobs it provides for local civilians--if the Navy is forced to stop dropping bombs and firing cannons on Vieques.

"Message to Puerto Rico: Be careful of what you wish for," a senior Pentagon official said.

The prospect of linking Roosevelt Roads and Vieques was first suggested last week by Sen. James M. Inhofe (R-Okla.), who chairs a subcommittee with jurisdiction over military bases. Inhofe argues that since support for training activities at Vieques represents a large part of Roosevelt Roads' mission, if one goes the other should too. The proposal has gained backing from congressional and Pentagon officials who hope that it will bring the Puerto Ricans to the negotiating table, and agree to allow renewed bombing, albeit at reduced levels. It does not appear to have had the desired effect.

"This proposition has been put to us as a threat, and I, personally, do not react well to threats," said Carlos Romero-Barcelo, the resident commissioner of Puerto Rico, the island's sole representative before Congress. Puerto Rico has commonwealth status, which affords its residents U.S. citizenship but limited political representation.

A specially appointed Pentagon panel is due to present a recommendation to the White House soon, according to a senior Pentagon official who said, "The options are not very complicated, but there are still a lot of politics to play out." The politics are considerably complicated by the recent controversy over Clinton's grant of clemency to members of a Puerto Rican pro-independence terrorist group and claims by prominent Republicans that the president was trying to curry favor with Puerto Rican voters in New York, where Hillary Rodham Clinton is preparing a run for the U.S. Senate.

In a July 26 handwritten note to his national security adviser, Samuel R. "Sandy" Berger, which was made public by Inhofe last week, Clinton said of the Navy use of Vieques: "This is wrong. I think they don't want us there. That's the main point. The Navy can find a way to work around it." But, with no apparent prospects for compromise, Clinton appears to be caught between admirals who insist that the Vieques test range is vital to national security and a loyal Democratic constituency that feels mistreated by the military.

The Navy's public position is that Vieques is unique, the only place off the East Coast where carrier-based aircraft, naval guns and Marine amphibious forces can conduct exercises simultaneously. In recent congressional testimony, Marine Corps Lt. Gen. Peter Pace, commander of Atlantic forces, used a football analogy to explain that while there are other sites where they can practice blocking and tackling, "the only place where we can scrimmage with the whole team together is Vieques."

Pacific forces conduct similar exercises on San Clemente Island off the California coast, which, unlike Vieques, is uninhabited.

The Navy's use of Vieques has long produced lawsuits, protests and extensive lobbying. But the opposition intensified after two bombs fell off target, though still on Navy property, killing a Vieques resident and wounding four others last April.

"Our position is that the Navy has dropped its last bomb on Puerto Rico," said Rep. Jose E. Serrano (D-N.Y.). "Heaven forbid they try to start again. You will see civil disobedience in Puerto Rico, in New York City, in Washington, D.C., all over."

In the fragmented world of Puerto Rican politics, Vieques has become a passionate and unifying cause. Four rival groups of activists and officials have set up four different protest sites on the target range that are manned continuously to prevent the Navy from resuming exercises.

The Navy concedes that it contributed to the ill will in Puerto Rico by failing to fulfill a 1983 agreement that ended the last round of protests. The Navy promised to promote economic development on Vieques and to take other steps to mitigate the situation.

"There've been an ongoing series of start-ups and then failures," Vice Adm. William J. Fallon, commander of the U.S. Second Fleet, told Congress last week.

In a bid to maintain its access to Vieques, Fallon said the Navy now realizes "our operations impinge on their livelihood down on the island." Offering to reduce the live ammunition exercises and making new promises of aid, Fallon said, "We would like to address, not only the national security imperatives for continuing our training on the island, but we'd also like to help enhance the quality of life of the people and their economic well-being."

So far Puerto Rican leaders are unconvinced by the Navy's arguments. "They have no credibility," said Romero-Barcelo.

Military: The U.S. military occupied two-thirds of the island in the 1940s and has used it for maneuvers and practice bombings. Residents have repeatedly protested the activity.

Civilian: The third of the island not occupied by the military is home to more than 9,000 people and is known for its beautiful beaches and a bioluminescent bay.