Seven years after the 9/11 suicide attacks and the launch of the "war on terror", America's most senior commanders have acknowledged that achieving victory is by no means certain, with conflicts still raging in Iraq and Afghanistan.
The bluster has all gone from President George Bush and even the most basic aim of taking Osama bin Laden "dead or alive", as he famously put it, remains a dim objective.
As America mourned the victims of the al-Qa'ida attacks on 11 September 2001, General David Petraeus, who led the US surge in Iraq, delivered a sobering judgement, saying he would never declare victory, that recent security gains were "not irreversible" and that a "long struggle" lay ahead.
Admiral Mike Mullen, the chairman of the US Joint Chiefs of Staff, told Congress that he did not believe the US and Nato were winning the second front against Islamists in Afghanistan, and that "we may be running out of time".
The entire strategy was in need of review and urgent steps had to be taken to combat Taliban fighters in Pakistan, where Pakistani military and secret police were giving them sanctuary, he said.
Yesterday brought yet another grim reminder of the difficulties ahead when militants in eastern Afghanistan killed two more US soldiers. Their deaths have made 2008 the deadliest year yet for US forces in the country that nurtured the 9/11 attackers.
It was also disclosed yesterday that George Bush had secretly signed executive orders authorising US forces to carry out ground operations inside Pakistan without the permission of the Pakistani government, as the Americans stepped up the hunt for al-Qa'ida and the group's leader.
The move, which extends the "war on terror" to another country, drew protests from Islamabad. The head of the Pakistani army, General Ashfaq Parvez Kayani, said his forces would not tolerate any infringement of Pakistani sovereignty.
Mr Bush, whose presidency has been shaped by his response to 9/11, used a commemorative ceremony in Washington to defend the achievements of the war. Future generations of Americans would learn of the "great struggle between the forces of freedom and forces of terror" which had taken place.
Flanked by his Vice-President, Dick Cheney, Mr Bush helped dedicate a memorial at the Pentagon and said that US armed forces had "taken the fight to the terrorists abroad so we do not have to face them here at home".
"Thanks to the brave men and women and all those who work to keep us safe, there has not been another attack on our soil in 2,557 days. The day will come when most Americans have no living memory of the events of September 11. When they visit this memorial ... they will learn that this generation of Americans met its duty. We did not tire, we did not falter, and we did not fail."
The speech was reminiscent of a pledge that he delivered on 7 October 2001, when the US launched its first offensive against the Taliban in Afghanistan. At that time, he said: "The battle is now joined on many fronts. We will not waver; we will not tire; we will not falter; and we will not fail."
General Petraeus, seen by the right in the US as the man who would save the Bush administration from ignominy over Iraq, is returning to the US from Baghdad to take over as the head of central command and to run operations in both Iraq and Afghanistan. Earlier this week, Mr Bush announced a cut of 8,000 US troops in Iraq by February, with some 4,500 to be sent to Afghanistan.
Summarising the Iraq situation, General Petraeus told the BBC it was "still hard but hopeful", that progress was "a bit more durable" but that the situation remained fragile. He did not know that he would ever use the word "victory". "This is not the sort of struggle where you take a hill, plant the flag and go home to a victory parade... it's not war with a simple slogan." In Afghanistan, "the trends... have not gone in the right direction ... and that had to be addressed."
Admiral Mullen said he had ordered a comprehensive military strategy to address the border region between Pakistan and Afghanistan. Until now, the US had remained tight-lipped about covert operations carried out within Pakistan, mainly through air strikes. Mr Musharraf had tended to turn a blind eye to the incursions when he held power.
However, in what was seen as a gesture that senior US officers had run out of patience with the Pakistanis, they admitted that a unit of Navy Seals special forces had conducted a prolonged ground attack in Pakistan last week.
The New York Times said that there was a growing belief among the US intelligence community that Pakistani intelligence services and senior figures in the military, including General Kayani, had foreknowledge of Islamist attacks such as the suicide bombing of the Indian embassy in Kabul. "It's very difficult to imagine he was not aware," a senior US official said.
If true, analysts pointed out, this meant that one of the central planks of Mr Bush's policy of arming and subsidising the Pakistani military, supposedly in an alliance against Islamic terrorists, had been an abject failure.