( dpa )- US President George W Bush Thursday celebrated the fifth anniversary of the establishment of the Department of Homeland Security, saying it was "hard to imagine" there had not been another "attack on our homeland" in the interim - but also warning of the need for vigilance.
Bush and the department's secretary, Michael Chertoff, noted the work that had been done to improve security at the nation's gateways since the September 11, 2001 terrorist attacks - work that Chertoff said had frustrated Islamist terrorists and forced them to turn to softer targets such as Europe.
"One of the reasons we're seeing more attacks in Europe is because they think it's easier," Chertoff was quoted as saying by the Washington Post online.
Chertoff cited attacks since 2004 in Madrid, London and Glasgow and disrupted plots in Denmark, Germany, Italy, France and Portugal.
Bush, in a separate speech to DHS workers, warned that the "danger to our country has not passed."
He noted numerous attacks that had been disrupted since the department was established, "including a plot to fly an airplane into the tallest building on the West Coast, and another to blow up passenger jets headed for America across the Atlantic Ocean."
He recalled al-Qaeda leader Osama bin Laden's threat two years ago that "operations were under preparation."
"The enemy remains active, deadly in its intent - and in the face of this danger, the United States must never let down its guard," he said, according to text of remarks released by the White House.
But he also noted the accomplishment of having avoided attacks in the intervening five years.
"I don't think we would have predicted that five years later there had not been another attack on us," he said.
The department was set up in 2003 to pull together 20 government bureaucracies, bringing under one roof responsibility for the security of goods coming in through sea and air ports, passengers coming in on planes, trains, ships and roads, passenger luggage and the like.
The US has also introduced new biometric and fingerprinting clearances for visitors, part of 20 layers of screening for air travel alone reaching "from hardened cockpit doors to federal air marshals," Chertoff noted.
Bush said that the companion to the homeland defence was the fight abroad - taking the "offense against the terrorists across the world."
"It is better to defeat them over there than to face them here in the United States," Bush said. "With our allies, we removed dangerous regimes in Iraq and Afghanistan that had harbored terrorists and had threatened our people."
He called the war "the great ideological struggle of our time."
Chertoff noted other improvements in security, including reinforcement of land borders through hundreds of miles of fencing, the doubling of the border patrol by late 2008 and the scanning of all sea-going cargo for radiation.
"We have made it much more difficult for dangerous people to enter the country to carry out attacks," Chertoff said.