Terror threat clouds 9/11 ceremonies
New York - President Barack Obama vowed on Saturday that the United States will never waver in its fight against terrorism as Americans get ready for the 10th anniversary of 9/11 under the shadow of another terror threat.
With the world marking a decade since the deadliest attack on US soil, and the tragedy seared into America's collective memory, communities honoured those lost in the disaster, while New York and Washington beefed up police presence at checkpoints, subway systems and airports on the eve of the anniversary.
Relatives of victims also gathered on a field in Pennsylvania where former president George W Bush and current Vice President Joe Biden will unveil a memorial to those who died aboard hijacked United Airlines Flight 93.
‘Terrorism will never win’
Even as US intelligence agencies chased down what officials said was a credible but unconfirmed threat of an al-Qaeda attack around the September 11 commemorations, Obama assured terrorism would never win.
"Ten years ago, ordinary Americans showed us the true meaning of courage when they rushed up those stairwells, into those flames, into that cockpit," the president said in his radio and internet address.
"We will protect the country we love and pass it safer, stronger and more prosperous to the next generation," he added.
"Today, America is strong and al-Qaeda is on the path to defeat."
In London, ex-British leader Tony Blair, who played a key role in responding to the 9/11 attacks, said Western powers should be praised for reducing the terrorist threat but warned leaders not to let down their guard.
"I think we have knocked out a lot of the al-Qaeda network," he told BBC radio, but "I don't think this is over. I think the radical Islamism which gave rise to this terrorist group is still with us."
The United States led an invasion of Afghanistan after September 11 to oust the Taliban which had been accused of harbouring 9/11 mastermind Osama bin Laden, but the Islamist group insisted on Saturday it had "no role whatsoever" in the attacks.
Fresh terror threats
The invasion of Afghanistan "will remain a permanent stigma on the face of Western democracy," the group warned in a statement.
The spectre of fresh threats hung over Americans as they readied to mark 9/11. A US official told AFP that "the general outlines of the initial report are three individuals coming into the country" last month, confirming the plot had links to militants in Pakistan.
US officials told US media that up to two of the operatives could be American citizens.
The New York Times reported that word of the plot was passed to US intelligence agents on Wednesday by an informer based in the border region between Afghanistan and Pakistan.
The informer said two US passport holders of Arab ancestry had left Afghanistan and reached the United States as recently as last week, according to the daily.
But the informer's report included only a vague physical description of the two men, the Times noted, with the first name for one given as Suliman, which is common in the Middle East.
Former national security adviser Frances Townsend told CNN on Friday that US spy networks had been alerted to a new threat after intercepting communications from a known, reliable operative in Pakistan.
"It's Washington or New York. A car bomb, three men. We know that one or two are US citizens," she said.
The intel prompted US security agencies to scour databases and flight manifests for clues.
"We're looking at travel records, times, dates that people may have travelled, passenger lists, itineraries," a US counterterrorism official, speaking on condition of anonymity, told the Washington Post.
Obama on Friday repeated his order for security agencies to redouble efforts to take all necessary precautions.
There have been no changes to his plans to attend Sunday ceremonies at Ground Zero in New York, and Shanksville, Pennsylvania.
On Saturday Bush joined current Defence Secretary Leon Panetta and Bush-era defence chief Donald Rumsfeld at a Pentagon wreath-laying ceremony to honour the Pentagon workers and airline passengers who died there.
Memories remain raw
Memories remain raw of the day when al-Qaeda hijackers slammed passenger planes into the World Trade Centre and the Pentagon. Almost 3 000 people were killed that day.
A fourth plane crashed in Shanksville, Pennsylvania when the passengers valiantly overpowered the hijackers, and Saturday's ceremony at the "field of honour" pays tribute to the 40 passengers and crew who died.
In New York, heavily armed police patrolled busy streets, trucks and cars were stopped and inspected at checkpoints and bomb-sniffing dogs scoured the subway. Similar actions were seen in Washington.
The anniversary has prompted extensive reflection on how the US fared in post-9/11 security, and while a recent Gallup poll showed Americans split on whether the United States or extremists are winning the "war on terror", officials were firm on US resolve to hunt down terrorists.
America's response to 9/11 showed that when attacked, "we will come and get you", Panetta warned on Friday as he thanked the firefighters and emergency teams who rushed to the Pentagon after it was struck.
"The people who attacked us on 9/11 were trying to weaken America, trying to hurt America," he said. "And instead they strengthened us."