"While our Nation is safer than it was seven years ago, the gravest threat to our people remains another terrorist attack," Bush said in his farewell address to the nation on Thursday.

The outgoing president would hand over the presidency to Barack Obama on January 20.

"Our enemies are patient and determined to strike again," Bush said in his nationally televised live speech in which he recollected the 9/11 attack and the decisions he took in its aftermath to protect the US from terrorists.

"America did nothing to seek or deserve this conflict. But we have been given solemn responsibilities, and we must meet them. We must resist complacency. We must keep our resolve. And we must never let down our guard," he said.

Recollecting the immediate aftermath of the terrorist attack on US, the outgoing president said, "This evening, my thoughts return to the first night I addressed you from this house on September 11, 2001."

This was the worst attack on America since Pearl Harbour as nearly 3,000 people died. "I remember standing in the rubble of the World Trade Centre three days later, surrounded by rescuers who had been working around the clock," he said.

Bush said seven year since the attack, most of the Americans might have been able to return to normal life as it had been before, but he has not. "I never did. Every morning, I received a briefing on the threats to our Nation. And I vowed to do everything in my power to keep us safe."

Under his presidency, not only the US has been secured by taking necessary measures to protect the country, but also the fight has been taken to the home of these terrorists, he said.

"With strong allies at our side, we have taken the fight to the terrorists and those who support them," Bush said.

"Afghanistan has gone from a nation where the Taliban harboured al Qaeda and stoned women in the streets to a young democracy that is fighting terror and encouraging girls to go to school. Iraq has gone from a brutal dictatorship and a sworn enemy of America to an Arab democracy at the heart of the Middle East and a friend of the United States," Bush said.

Bush, however, conceded that there was legitimate debate about many of his decisions. "But there can be little debate about the results. America has gone more than seven years without another terrorist attack on our soil," he said.