America is on high alert following the botched car bombing of Times Square this Saturday, as authorities shut down a major New York City bridge briefly late Wednesday, sending bomb squad investigators after an abandoned truck was reported.
The police found no explosives.
Lieutenant Mike Wysokowski told AFP no bomb was found on the truck abandoned on the Robert F. Kennedy Bridge, also known as the Triboro Bridge.
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Earlier, US officials have tightened security in the wake of the botched Times Square bomb plot, amid a growing global probe into a Pakistani-American suspect's possible links to foreign militant groups.
Washington tightened "no-fly" procedures after the chief suspect, Faisal Shahzad, managed to board a flight to Dubai from New York on Monday just before being apprehended.
The Pakistani-born US citizen, accused of planting a large but poorly made car bomb in Times Square on Saturday, was undergoing a second day of questioning.
Officials gave no word on when he would appear in court, but a law enforcement source told AFP he would almost certainly not appear on Wednesday.
Analysts said the delay in presenting Shahzad before a judge indicated he had still not asked for a lawyer, and that statements by officials saying Shahzad has been cooperative with interrogators
since his arrest were accurate.
"If he'd decided to get a lawyer, we would have heard very well by now," said Centre for Strategic and International Studies expert Thomas Sanderson.
"The fact that we haven't and the fact that he appears to be spilling his guts lends even more credence to the claims that he is an amateur."
Shahzad faces life in prison
Shahzad, 30, has been charged with five counts of terrorism, including attempted use of "a weapon of mass destruction." He faces life in prison if convicted.
US authorities are pressing now to discover whether there is a link to organised terrorism, in Pakistan or elsewhere.
Though the attack bore the hallmarks of an amateur with only basic technical knowledge, Shahzad has allegedly admitted that he received "bomb-making training" in Pakistan's lawless Waziristan region.
In Islamabad, the US ambassador consulted with Pakistani leaders, who pledged to investigate possible links to Saturday's near horror.
The White House sounded an optimistic note, saying al-Qaeda was turning to smaller, "less sophisticated" attacks as its capacity to mount September 11-style spectaculars diminished thanks to US action.
Attacks should be expected as retaliation for drone missile strikes
But in an interview with CBS television, Pakistani Foreign Minister Shah Mehmood Qureshi warned that increased attacks should be expected in "retaliation" for US drone missile strikes killing anti-US insurgent leaders in Pakistan.
"You could expect that.... Let's not be naive," Qureshi said.
So far the only group to claim responsibility for the Times Square plot is a Pakistani Taliban group.
Even if the bomb was a dud and the suspect was rapidly caught, the incident rocked the US security establishment – particularly as Shahzad managed to board a plane before being nabbed.
The attack was stopped when a street vendor spotted smoke coming from the rigged car and alerted police.
Fifty three hours later, while the target of a massive manhunt, Shahzad drove to JFK airport, bought a ticket, passed passport control and boarded an Emirates Airlines flight before being arrested after the plane left the gate.
Attorney General Eric Holder insisted Tuesday there was never "any fear that we were in danger of losing him."
But US aviation officials said on Wednesday they had stepped up security requirements demanding airlines check "no fly" lists within two hours of learning of a "special" name, instead of the previous requirement of 24 hours.
"In his case, the airline seemingly didn't check the name, and the suspect was allowed to purchase a ticket and obtain a boarding pass," a Transportation Security Administration official told AFP.
Mayor Bloomberg presses Congress for more security funds
New York Mayor Michael Bloomberg used Saturday's incident to press Congress for more city security funds and to get MP's to ban the sale of weapons to people on an FBI terror watchlist.
"At a time when the threat of terrorism is still very real, as we in New York city know all too well, I think it is imperative that Congress close this terror gap in our gun laws, and close it quickly," he said.
The main question now is whether Shahzad had outside help or was acting on behalf of a larger group.
Pakistan's military said it had yet to establish a link between Shahzad, who is the son of a retired air force officer, and the country's main militant stronghold in Waziristan.
"Until and unless the link is established, it will be premature to say that he had gone there," army spokesman Athar Abbas told AFP.
Waziristan is the powerbase of Tehreek-e-Taliban Pakistan, which claimed Saturday's attempted attack.
