MANUEL ERNESTO RIVERA
  Associated Press Writer

  VIEQUES, Puerto Rico - Navy security officers fired tear gas at protesters who hurled rocks over a fence during bombing exercises on the island of
  Vieques, authorities said Thursday.

  Two servicemen were hit by rocks but were not injured in the confrontation Wednesday night, said Navy spokeswoman Lt. Cmdr. Kim Dixon.

  The security officers, assigned to guard a fence between Navy lands and a protesters' camp, fired the tear gas at demonstrators who were using
  slingshots to throw rocks, Dixon said. It was unclear how many protesters were involved.

  A third day of military exercises on Vieques began Thursday morning with the destroyer USS Briscoe firing inert 5-inch shells and flare tracers in
  ship-to-shore training, Dixon said.

  The guided missile destroyer USS Mitscher also was to participate, along with a squadron of F-14s and F-18s dropping inert bombs.

  Wednesday night's clash did not affect the training at the bombing range several miles away, Dixon said.

  President Bush has promised the Navy will withdraw from Vieques by May 2003, but as the United States moves closer to a conflict with Iraq, some here
  believe the Navy departure will be delayed.

  At least 27 members of Congress have urged Bush to issue an executive order guaranteeing the Navy's departure.

  The latest exercises in the U.S. territory - the third since the Sept. 11 terrorist attacks - involve 10 ships, two attack submarines and about 80 planes in
  the USS Harry S. Truman Battle Group.

  The military has used the bombing range for more than six decades. Opposition grew when a civilian guard was killed by two bombs dropped off-target in
  1999. Since then, only inert bombs have been used.