The unannounced decision to sail the second convoy of reflagged Kuwaiti tankers and U.S. warship escorts into the Persian Gulf yesterday caught off-guard some key Pentagon officials who said they believed the operation had been delayed for several more days.

The Washington Post and other news organizations reported Friday that Pentagon sources said the operation had been delayed several days to allow new mine-sweeping equipment to arrive on the scene and to adequately prepare for other possible threats.

Pentagon officials, citing growing alarm among top military leaders over leaks to the news media about the missions, said the military leadership has moved in recent days to tighten the circle of participants allowed access to details of the operation.

Pentagon officials said most of those details are being decided by a small group of military leaders including the commander of the U.S. Navy's Middle East task force, the Florida-based chief of the Pentagon's Central Command, the Joint Chiefs of Staff and Defense Secretary Caspar W. Weinberger.

Top Navy officials said they have not been provided much of the day-to-day operational information about the mission, although the equipment and facilities that are being used are primarily the Navy's.

"We're not discussing schedules or plans," one Defense Department official said yesterday.

Pentagon officials have said they fear that leaks about the operation could endanger the safety of ships passing through the volatile Strait of Hormuz and Persian Gulf.

Unlike the previous mission into the gulf, in which the reflagged oil tanker Bridgeton struck a submerged mine, the Pentagon did not assemble a news media pool on board any of the escorting ships to report on the operations.

The Defense Department did not publicly acknowledge that the

operation was under way until al- most 24 hours after it had begun, despite news reports from the

Middle East early yesterday morning.

While officials left unaware of the convoy's movement yesterday said they do not believe Pentagon officials had used a disinformation campaign to camouflage details of the mission, several said that official internal briefings on the operation have been intentionally vague and subject to wide-ranging interpretation in recent days.

"I didn't have any information that it was starting," said one source. "But I couldn't say that it was disinformation. We've never been given exact dates, but everybody was interpreting that they were waiting for mine sweepers and helicopters."

A team of eight sophisticated Sea Stallion mine-sweeping helicopters is expected to arrive in the gulf on the transport ship USS Guadalcanal within days, according to Pentagon officials.

One Pentagon official said that despite the Defense Department's stated concern over the safety of the operation, many of the schedules are being driven by commercial shipping interests.

"They {the reflagged Kuwaiti tankers} are out there to make money. They've got customers and deadlines."

Weinberger and the chairman of the Joint Chiefs briefed top congressional leaders about some aspects of the Persian Gulf operation late last week, but members of Congress present at the session said they were not provided dates for the convoys.

Military officials sharply criticized some congressional leaders who revealed proposed dates for the missions after a closed briefing several weeks ago.

It was after that briefing that some congressional leaders said the operation that started in the early morning hours yesterday had originally been scheduled to start last Thursday.