Former Pennsylvania Gov. Tom Ridge was sworn in on Monday as the first U.S. director of homeland security with a "difficult but not impossible" task -- head off terrorism in America before it happens again. 
With the nation on edge over feared reprisals for U.S.-led air strikes on Afghanistan, President Bush and his entire Cabinet watched in the East Room of the White House as Ridge raised his right hand, placed his left on a Bible held by his teen-age daughter Lesley, and repeated the oath of office. 
After he swore to "support and defend the Constitution of the United States against all enemies, foreign and domestic," Ridge leaned over and whispered to his daughter, "I love you." 
The Cabinet-level position has enormous scope, from protecting energy production, information and transport systems to reviewing all federal emergency response plans. 
Bush said he had found "the right man" to forge an effective anti-terrorism strategy for a nation traumatized by the Sept. 11 attacks that destroyed the World Trade Center, damaged the Pentagon and killed more than 5,500 people. 
Ridge, a 56-year-old decorated Vietnam combat veteran and former congressman who was widely rumored as a candidate for the job of vice president or defense secretary when the newly elected Bush was choosing his Cabinet, has been a friend of the president's family for two decades. 
"The size and scope of this challenge are immense," Ridge said. Comparing it to building the transcontinental railroad, fighting World War Two or putting a man on the moon, he added, "The task before us is difficult, but not impossible." 
Acknowledging the job would take unprecedented cooperation and communication between government departments and agencies, Ridge cautioned, "The only turf we should be worried about protecting is the turf we stand on." 
Bush and other key members of the government have warned of possible retaliatory attacks against Americans in response to the administration's war on terrorism to punish the Islamic militants blamed for last month's attacks. 
The number of possible targets is endless, from nuclear power plants to crowded subway trains. Many Americans have been buying gas masks and antibiotics out of fear of attack with chemical or biological weapons. 
"I know that many Americans at this time have fears," Bush said before he signed an executive order creating the homeland security post. "We've learned that America is not immune from attack. We've seen that evil is real." 
"America is going to be prepared," he declared. 
Attorney General John Ashcroft said on Monday 614 people had been arrested or detained since Sept. 11, but that law enforcement officials were still looking for 229 others. 
"I encourage all Americans to continue to have a heightened sense of awareness of their surroundings," Ashcroft said. "Every American should be vigilant and we are counting on each American to help defend our nation in this war." 
Some experts and lawmakers say it is almost impossible to safeguard such a vast nation, and have urged Congress and the White House to give Ridge greater powers to mobilize a nationwide defense that would reassure the public. 
"No homeland czar can possibly hope to coordinate the almost hopeless dispersal of authority that currently characterizes the 40 or more agencies ... with some piece of responsibility for protecting the homeland," warned former Sen. Gary Hart, co-chair of the U.S. Commission on National Security for the 21st Century. 
The White House said Ridge would have a direct staff of 12 and about 100 more who are at other federal agencies and who will report to him. He will have an office in the West Wing and will report directly to Bush. 
His position is not subject to Senate confirmation and White House spokesman Ari Fleischer told reporters on Monday Bush saw no need for it. He said Ridge would be "very senior," attending Cabinet meetings and national security briefings. 
Despite heightened security after the attacks, especially at U.S. airports, experts say the nation's borders remain porous in some places, and it would be impossible to defend every potential target because there are so many. At the same time, congressional investigators say federal, state and local health agencies are poorly coordinated and ill equipped. 
An attack using chemical or biological agents could sicken thousands of Americans before it is even detected. But experts say local doctors, nurses and emergency medical technicians, who would be the first on the scene, have had little training with such diseases as smallpox and anthrax.