VIEQUES, Puerto Rico -- Three years after U.S. military exercises were halted here, tempers still run hot when residents recall six decades of naval bombardments that transformed parts of this tropical island paradise into lands resembling the surface of the moon.

These days, residents' hostilities are centered on why it is taking the U.S. government so long to begin what surely will become among the most ambitious Superfund cleanup campaigns in American history.

But while the U.S. Environmental Protection Agency says its plans are progressing on schedule, this bit of news is serving to stoke fresh local hostilities: Bombs are going off in Vieques again, and the blasts may last eight years or more.

This time the explosions are part of the military's program to detonate missiles, rockets and other ordnance that struck the ground but didn't explode during the years of military exercises. And until the work is complete, officials said, there can be no meaningful environmental cleanup here.

"It's all a bit much to take," said Nilda Medina Diaz, chairwoman of the Committee for the Rescue and Development of Vieques, a community group that helped lead a public fight that persuaded the Navy to leave Vieques. "A lot of us who live in Vieques look around and ask, `Where's the cleanup?'"

These developments are disturbing, Medina Diaz and others say, because they believe substances such as depleted uranium, mercury, napalm and other toxic chemicals left in the soil from the military exercises are seeping into the ocean, damaging coral reefs and contaminating wildlife. There's also a concern that dust from the new explosions might pose a health hazard to island residents.

No risk, EPA says

"Our work is progressing as fast as it can," said Jose Font, deputy director of the EPA's Caribbean Environmental Protection Division.

He said there is no evidence to suggest that the new detonations pose a risk to anyone or that any contaminants on the ground pose a risk to plants or wildlife.

What is certain, however, is that the explosions are upsetting homeowners on this island and startling fishermen casting their nets a mile or so away from a shuttered military base. And not surprisingly, the sounds are upsetting activists who spearheaded years of civil disobedience and other protests that prompted President Bush to end military exercises on Vieques.

Maria de Lourdes Santiago, a member of Puerto Rico's Senate, said what's happening in Vieques is not ideal, but there really is no better alternative to clear the way for a full environmental cleanup without the detonations. In the end, she said, everyone wants the same thing: restoring Vieques into a tropical paradise "so residents' health and economy can thrive."

The military's presence in Vieques dates to World War II, when the U.S. government acquired about two-thirds of the island, wedging thousands of residents onto grounds between military encampments on the eastern and western ends of this 5-mile-long by 3-mile-wide island.

The U.S. North Atlantic Fleet valued Vieques as a good location for amphibious assault landings, shelling, aerial bombardment and other exercises. Long-standing tensions between the military and many of the island's 8,000 residents turned hostile in 1999 when a Navy warplane accidentally bombed a military observation tower, killing a civilian Puerto Rican security guard.

But long before that, poor communication between the U.S. military and residents generated years of mistrust. For instance, little was known until recently about Navy tests of napalm bombs or missiles containing uranium during the 1990s, or of military testing here during the 1960s of chemical and germ warfare agents.

The military also acknowledged spraying a Marine unit with trioctyl phosphate, an agent that has caused cancer in lab animals, as a substitute for the lethal VX nerve agent.

The return of explosions and the slow pace of EPA efforts on the island aren't a big surprise to many Vieques residents.

"Unfortunately, when you live in Vieques, you have to get used to surprises like more bombing," said Jose Hernandez, 43, while constructing a home about 200 yards from Camp Garcia, where the military carried out the bulk of its maneuvers.

"You ever get woken up by bombing off in the distance? You don't get used to it," Hernandez said. Fishermen say they must take to the waters or risk joining the local welfare lines. That means they have to go where the fish are, they explained.

"The bombing, as you might imagine, makes this work very difficult," said Melvin Guzman Torres, 30, before embarking on a spear-fishing expedition one morning.

The Navy says fishermen are taking their lives into their own hands by going so close to the closed camp, where unexploded bombs litter the grounds and missile fins protrude from the shores.