W By Josh Meyer and Greg Miller

ASHINGTON – After more than a year of suspense over whether Osama bin Laden is dead or alive, U.S. officials said they believe the man heard on an audiotape Tuesday praising recent attacks against civilians in Indonesia and Russia and urging new strikes on the United States and its allies is the terrorist mastermind.

Several U.S. officials cautioned that the National Security Agency, CIA and other authorities would continue to analyze the high-quality audiotape throughout the night for conclusive confirmation that it is the voice of bin Laden. But they said they believe the founder and leader of the al-Qaida network – silent, hunted and unseen since last year – is the man heard issuing a series of threats and calls to arms to Muslims around the world.

The 4 1/2-minute tape was provided to the Qatar-based Al Jazeera television network and broadcast globally beginning Tuesday afternoon under the heading “new audio statement by Al Qaeda leader Osama bin Laden … to the peoples of the countries allied with the tyrannical U.S. government,” according to a transcript released by U.S. officials Tuesday evening.

On the tape, the man identified as bin Laden refers to recent terrorist attacks in Bali, Tunisia, Yemen, Pakistan and Moscow and says that they were in response to those countries’ support of the United States in its military strikes in Afghanistan and in other alleged acts of aggression against Muslims, including in Iraq.

The purported comments by bin Laden come at a troubling time as the United States spearheads a coalition gearing up for war with Iraq and amid growing indications that al-Qaida is regrouping and planning more attacks in far-flung corners of the world.

The tape rang alarm bells at the White House, the CIA, Pentagon and elsewhere in Washington, officials said, because bin Laden has been known to make such public pronouncements just before a terrorist strike, as was the case before al-Qaida truck bombs killed 224 people at two U.S. embassies in Africa in 1998.

Several U.S. officials said that an initial analysis of the tape, based on comparison with existing “voiceprints” of bin Laden, indicate that it is authentic and made in recent weeks – the first concrete evidence that the Saudi fugitive survived the punishing military attacks in Afghanistan and perhaps the most aggressive global manhunt in history. Many U.S. officials, including the FBI’s top counterterrorism authority, had said publicly that they believed bin Laden was probably dead.

“I don’t doubt that it’s bin Laden but there is no reason to rush to judgment on this,” said one U.S. official, speaking on condition of anonymity. “We are waiting for our analysts to check all possibilities. Significant portions of it could be bin Laden with other parts spliced in.”

“Initial reports can be wrong,” cautioned the official. “But we’re hearing that (technical) people are saying, `Yes, it sounds like him.’ “

Several counterterrorism experts said bin Laden’s apparent resurfacing might have been triggered by the increasing drumbeat of war with Iraq.

“The confrontation with Iraq is perfect grist for the jihadist mill,” said Daniel Benjamin, a former counterterrorism expert at the National Security Council and recent co-author of a book on al-Qaida and its conflicts with the West. “Even though he has no sympathy for Saddam Hussein or the regime there, bin Laden has always cast the confrontation with Iraq as another example of the struggle between the infidels and the crusaders” and the followers of Islam.

Moreover, bin Laden’s emergence would underscore what critics of an Iraq invasion have argued – that the war on terrorism is unfinished and that an assault on Baghdad would stretch U.S. resources too thin. Senior military officials seem increasingly impatient with the progress of the war on terrorism, particularly the often fruitless sweeps of territory along the Afghanistan-Pakistan border.

Last week, Gen. Richard B. Myers, chairman of the Joint Chiefs of Staff, said he thought the United States had “lost a little momentum” in the hunt for al-Qaida, and argued for putting greater emphasis on shoring up the Afghan government.

U.S. counterterrorism authorities – and British Prime Minister Tony Blair – have cautioned in recent days that there has been an alarming spike in the kind of intelligence “chatter” that normally precedes a major terrorist attack, at a level unseen since the assaults on the World Trade Center and the Pentagon.

At the Justice Department and FBI, the airing of the tape put authorities on an even higher state of war footing than they had been previously, one official said. “Unfortunately, every time he surfaces, something really bad follows,” the official said. “It makes us have to be even more on our guard, which is a hard thing to do because we are already at a very heightened state of alert. “

If bin Laden’s voice is confirmed, it is sure to renew hand-wringing over how the al-Qaida leader escaped U.S. forces who had him all but trapped in the snowy mountains near Tora Bora, Afghanistan, last December.

For two weeks, allied forces and B-52 bombers pounded al-Qaida fighters dug into the cavernous and rocky terrain. But when it was over, there was no sign of bin Laden, and it was clear that hundreds of his followers had escaped.

The missed opportunity is regarded by many as a major blunder in the Afghan war. Gen. Tommy Franks, leader of U.S. Central Command, has been heavily criticized for failing to choke off exits with American troops and relying on Afghan forces that in hindsight don’t seem to have been up to the task.

The question of whether Bin Laden is alive remains a sensitive one for the Bush administration as well.

In the immediate aftermath of Sept. 11, President Bush talked of taking him “dead or alive.” In later months, he began to argue that capturing “one man” was not the primary objective of the war. More recently, senior administration officials have bristled when the subject is broached.

On Tuesday, a spokesman for the White House and National Security Council said Bush would make no comment on the tape until more information was available as to whether the voice was indeed bin Laden.

On the tape, the man asks: “Why should fear, killing, destruction, displacement, orphaning and widowing continue to be our lot, while security, stability and happiness be your lot? It is time we get even.

“You will be killed just as you kill, and will be bombed just as you bomb. And expect more that will further distress you.”

U.S. officials said they began analyzing the tape even as it was being broadcast and that they were trying to determine how the tape came into the possession of the satellite network, which has been used frequently by bin Laden and other al-Qaida leaders to get their militant messages broadcast to the world.

At the White House, spokesman Sean McCormack said, “We are looking into it and have not made any judgments yet as to whose voice is on the tape. It will be analyzed by the intelligence community. “