Rafael Torres, a former security guard at the U.S. Navy base here, said he still hears noises in his head--a sound like the fighter jet that in 1995 hurled two cement-filled projectiles a few feet from where he was standing during war maneuvers.

"The other day I was sleeping in my armchair, and I dove on the floor when I heard airplanes buzzing in my ears," said Torres, 49, who has since retired with a disability pension because of psychological trauma from the accident.

He said one bomb struck the three-story observation post he was guarding, crashing through the top two floors. The second landed feet away from where he stood, spewing chunks of cement.

Torres didn't realize it at the time, but this narrow miss foreshadowed a much more serious accident. Last April 19, one of Torres's co-workers, David Sanes Rodriguez, was pulling duty at the same post when a Navy F-18 dumped two 5,000-pound bombs about 1.9 miles off course. Unlike the inert practice bombs Torres encountered, these projectiles packed live explosives. Sanes was killed, and four other base employees were injured.

The incident has stirred widespread political opposition to the Navy's nearly 60-year hegemony over this Puerto Rican island-municipality, which 9,300 residents have reluctantly shared with a huge bombing range. Now the Pentagon is in danger of losing its premier naval training facility, the Atlantic Fleet Weapons Training Facility in Vieques, judged by military analysts to be an "irreplaceable" national security asset and the only site in the Atlantic where the military can stage integrated sea and air training.

Capt. James K. Stark Jr., who as commanding officer of the Roosevelt Roads Naval Station is in charge of the Vieques facility, said crews on all ships in the U.S. Atlantic Fleet sharpen their skills here regularly and visit the Vieques target range for a final tuneup before steaming off to overseas conflict. Simulating "the fog of war" with the use of live munitions is vital to success in actual combat, he said.

"When you steam off to battle you're either ready or you're not," Stark said. "If you're not, that means casualties. That means more POWs. That means less precision and longer campaigns. You a pay a price for all this in war, and that price is blood."

The Navy says this is the first casualty on the ground in more than half a century of exercises. But Puerto Rico officials have decided that enough blood has been spilled at Vieques.

"The life of a single Puerto Rican is priceless, and we're not willing to run the risk of losing another life," said Puerto Rico Secretary of State Norma Burgos. "How many people have to die before they realize it's time to go?"

Since Sanes's death, Puerto Rico Gov. Pedro Rossello has petitioned President Clinton and Defense Secretary William S. Cohen for a permanent cease-fire in Vieques and the return of Navy-held lands. The Rossello-appointed Special Commission on Vieques, in a June 25 report, charged that Navy practices in Vieques constitute violations of residents' fundamental rights and lack adequate safeguards to protect against potential mishaps in civilian areas.

The report did collateral damage to the Navy's image, in particular its disclosure that U.S. forces training in Vieques have used napalm and uranium-laced munitions during war games here.

The report also called for an epidemiological study to determine whether Navy practices are linked to Vieques's cancer rate--by far the highest of any of Puerto Rico's 78 municipalities, studies have shown. The report also cites gross environmental abuses, including the destruction of endangered species habitats, and calls for action against the Navy under "environmental justice" statutes.

The deep-seated resentment felt by many in Vieques--who are U.S. citizens, as all Puerto Ricans have been since 1917--is echoed by Jose Silva, 59, a street-side kiosk owner who was born the year before the Navy arrived in 1941 and expropriated three-quarters of the island. Holding up a bowling pin-sized bomb he collected as a "souvenir," Silva said: "There are two bases here and no jobs for anybody. The people here are dying of cancer by the dozens," including nine members of his own family, he said. "The Navy wants to carbonize us all."

Vieques residents are displaying a more militant anti-Navy stance these days. Municipal workers can be spotted in T-shirts emblazoned with the slogan: "If the Navy doesn't leave, we're going to kick it out." White flags, symbolic of the quest for "peace for Vieques," are festooned about the civilian area--a four-mile-wide strip in the center of this lush, 21-mile-long island. Fenced in between twin military bases on either side of them and besieged by the continual blasting of military exercises--200 to 250 days a year--some residents liken their plight to that of prisoners of war.

The cause has gathered some support on Capitol Hill. Democratic Reps. Luis V. Gutierrez (Ill.), Robert Menendez (N.J.) and Nydia M. Velazquez (N.Y.), as well as Sen. Charles E. Schumer (D-N.Y.), earlier this month called for the Navy to vacate Vieques. And it has caught the attention of Puerto Rican voters in New York, where first lady Hillary Rodham Clinton is exploring a bid for the Senate. Democratic Councilman Jose Rivera of the Bronx and Dennis Rivera, leader of the local hospital workers union, are organizing a Sept. 11 protest that they hope will turn out tens of thousands of demonstrators.

Vieques residents have enjoyed the tranquillity of a temporary cease-fire, as the Navy suspended exercises following Sanes's death. But Navy officials have announced plans to resume training missions in September. First, they will have to evict protesters who have formed at least four renegade settlement camps on Navy land.

The future of the controversy will be shaped by the findings of a presidential panel that is to issue its findings to Defense Secretary Cohen, possibly by the end of this month. Sentiment on the island is that the Special Panel on Military Operations in Vieques--three of whose members are retired military officers--will not recommend evicting the Navy. They are hopeful, nonetheless, that President Clinton would override any recommendations for a compromise arrangement.

In the past, many top Puerto Rico officials seemed indifferent about the Navy's control of Vieques. But that is changing.

Burgos, the secretary of state, said the Rossello administration will not accept anything short of the Navy's full withdrawal, citing spotty compliance with a 1983 pact in which the Navy was supposed to improve its stewardship of Vieques.

She said the Navy has "no credibility" in Puerto Rico and alleged that Navy officials lied to her in public hearings about using napalm and uranium on the island and about letting foreign militaries use the target range. In May, the Navy said that it mistakenly fired 267 rounds tipped with depleted uranium at Vieques in February in violation of federal laws.

Navy officials counter that Vieques, located eight miles from Roosevelt Roads--the largest Navy base in the world--is "uniquely" suited for amphibious training exercises and would cost $3.5 billion to replace.

Vieques is the only such facility in the Atlantic--the Navy has one on the island of San Clemente in the Pacific. They say all 18 alternative sites considered so far pose logistical problems such as the disruption of shipping lanes, commercial airplane routes or wildlife habitat.

"Give me a couple of billion dollars and make me God, and I'll go someplace else in a nanosecond," said base commander Stark. "But that's not the reality of it."

Staff writer Bradley Graham in Washington contributed to this report.

CAPTION: Jesse L. Jackson, in Vieques last Friday to support those opposing the Navy presence, greets students as he walks with the archbishop of San Juan.

CAPTION: Jesse L. Jackson talks with Puerto Rican independence leader Ruben Berrios, center, and Archbishop of San Juan Roberto Gonzalez last Friday on the shore of Vieques, Puerto Rico.