9/11 anniversary: Attacks made US stronger, Obama says
The United States is stronger 10 years on from the 9/11 attacks and al-Qaeda is "on the path to defeat", President Barack Obama has said.
"As a resilient nation, we will carry on," he told Americans on the eve of the anniversary of the attacks.
Events are being held to commemorate the victims, amid warnings that al-Qaeda is behind a new "credible but unconfirmed" threat to Americans.
Nearly 3,000 people died on 9/11 in New York, Washington and Pennsylvania.
On Sunday, Mr Obama will travel to all three sites.
"Thanks to the tireless efforts of our military personnel and our intelligence, law enforcement and homeland security professionals, there should be no doubt: today, America is stronger and al-Qaeda is on the path to defeat," President Obama said in his weekly address.
"Yes we face a determined foe, and make no mistake - they will keep trying to hit us again. But as we are showing again this weekend, we remain vigilant," he said.
"Across the Middle East and North Africa a new generation of citizens is showing that the future belongs to those that want to build, not destroy."
'Worst day of my life'
Security has been tightened in New York and Washington after the reported threat in the run-up to Sunday's anniversary. US officials believe al-Qaeda may have sent attackers, some of them possibly US citizens, to bomb one of the cities.
Counter-terrorism officials reportedly received a tip-off from a CIA informant last week. They are still trying to corroborate the reported threat.
Events commemorating the anniversary of the attacks are scheduled throughout the weekend.
On Saturday thousands of people in New York joined hands to remember those killed.
"Every year, I kind of, don't handle it, but it's the 10th year and so I felt like it was important to make a statement," one woman, Juliet Di Frenza, told Reuters.
"It was the worst day of my life."
On Sunday, President Obama will visit the World Trade Center site, the Pentagon and a memorial ceremony in Shanksville, Pennsylvania - where the fourth hijacked plane, United 93, came down.
He will be joined in New York by former President George W Bush.
Police in New York are carrying out spot checks in the city's subway and have tightened security on roads, bridges and tunnels.
Checkpoints have been set up across Manhattan where police are scanning for radiation and stolen licence plates, causing serious traffic congestion around the city.
Members of the public are being asked to report abandoned or suspicious vehicles.
On Friday, US Secretary of State Hillary Clinton said the threat was being taken very seriously by state and federal authorities.
Counter-terrorism officials were particularly concerned by the threat because documents seized during the raid on Osama Bin Laden's Pakistan compound in May showed al-Qaeda was considering strikes to coincide with the anniversary, Mrs Clinton said.
Reports suggest that intelligence gathered in Pakistan points to a possible car or truck bomb attack against New York or Washington.
US TV network ABC News has reported that three individuals - one a US citizen - entered the US in August aiming to carry out an attack.
Reuters news agency has reported US officials as saying the threat could be linked to al-Qaeda leader Ayman al-Zawahri - Osama Bin Laden's deputy, who took over leadership of the group after Bin Laden was killed by US soldiers in Pakistan in May.