The skipper of the USS Stark had only seconds to react to the Iraqi jet attack last month because the radar warning that would justify taking defensive action did not come until just before the first of two Exocet missiles was fired at his ship, according to a Pentagon chronology released yesterday.

The Stark, cruising in the Persian Gulf, detected the searching radar beams of the Iraqi Mirage F1 fighter at 10:06 p.m. on May 17. It is not unusual to be "painted" by such search beams and that alone does not justify firing on the approaching aircraft, according to Navy officers who have served in the gulf.

Three minutes later, the pilot locked onto the ship with his radar in the way that does justify defensive action -- which can range from turning the ship's stern toward the attacker to put the Phalanx rapid-fire gun in position to fire to activating missiles and guns. Rather than following the usual tactic in the gulf of keeping the radar locked on the ship for several minutes before veering off or firing, the Iraqi pilot went right into the launch mode, according to the Defense Department.

One minute later, it said, the Stark had the radar that guides its antiaircraft missiles and 76-mm gunfire locked onto the Mirage. That is the last step before firing. But five seconds later the first Exocet hit, and 25 seconds after that a second missile burrowed into the ship.

The first missile was a dud, the Pentagon said, but the second exploded in one of the crew's sleeping compartments, setting off fires that caused many of the 37 deaths on board.

The Pentagon report confirmed that Capt. Glenn R. Brindel, skipper of the Stark, issued two radio warnings to the Iraqi pilot to change course once he had locked on the ship.

"In the first warning" -- sent over the international "on guard" radio station that Iraqi pilots are supposed to monitor -- "USS Stark identified herself as a U.S. Navy warship on a bearing of 78 degrees at 12 miles," the Pentagon said. "Thirty-seven seconds later a second warning was issued stating USS Stark's position as bearing 76 degrees at 11 nautical miles from the aircraft. No reply to either warning was received by AWACS {surveillance aircraft} or USS Stark."

Iraq has asserted that the Stark was inside the "exclusion zone" of the gulf where Iraq had warned that ships would be subject to attack, the Pentagon said. The U.S. government disputes the contention.

The Iraqis base their assertion on the navigation system in the fighter plane cockpit, the Pentagon said, adding that "we are convinced Stark was 10 to 15 nautical miles outside" that zone. The Pentagon said it had received a "wealth of position data" on the Stark from that ship, the AWACS plane that monitored the attack and two other ships in the area -- the USS Coontz and USS LaSalle.

Navy Secretary James H. Webb Jr. at a luncheon yesterday with Washington Post editors and reporters said he had no doubt that the Stark was outside the exclusion zone. He declined to comment on the performance of the Stark's captain since he could end up being the reviewing authority if the captain is court-martialed.

Webb stressed that one lesson of the attack on the Stark is that rules of engagement for the Persian Gulf must be clarified. He pledged to back up any skipper who takes action against an intruding aircraft. He said he and Defense Secretary Caspar W. Weinberger agree that U.S. military personnel must not be sent into a high-risk area with a fuzzy mission.

Webb, a combat veteran of Vietnam, said "you cannot send a military unit into a combat environment and not give him a clear military mission with the potential that it will escalate. You don't tell them they're there for presence," as was the case with the Marines in Lebanon.

"Even with the proper rules of engagement," he said, "you have a mindset in a lot of commanders that in some cases has caused them to think twice before they pull the trigger."

The Pentagon in its report issued yesterday said the Iraqis asserted that "not until the following day" did the Iraqi pilot realize "through the news media that the vessel he attacked was the USS Stark."