DAVOS, Switzerland_More than four years after the Sept. 11 attacks, FBI director Robert Mueller said Thursday the United States is doing a much better job of integrating domestic and foreign intelligence and acting on it to fight terrorism around the world.
But the U.S. law enforcement official cautioned that "nothing is perfect and nothing is certain."
"We are safer but not totally safe," Mueller said in an interview on the sidelines of the World Economic Forum, the annual gathering of top business and government officials where he was on panels discussing information security and global risks.
In the eyes of the FBI, he said, fighting terrorism remains the top national security priority followed by counterintelligence and cyber security.
Mueller said a key lesson from the 2001 al-Qaida terrorist attacks in the United States was the need to break down "the walls" that divided domestic law enforcement and foreign intelligence in the past, "so you have a relatively free exchange of information with appropriate security safeguards."
Since Sept. 11, 2001, he said, U.S. officials have recognized the importance of using all information to determine "who intends to hurt the United States or the United States' interests around the world."
"For us, it is not just having a terrorist event happening and then gathering the evidence to put it in a courtroom to convict somebody after we're able to identify him, detain him and extradite him," Mueller said.
"For us, it's taking the information domestically, integrating it with what we know from the other intelligence agencies in the U.S., and integrating it with intelligence from our counterparts from overseas to get a fuller picture of what the enemy intends, in this case al-Qaida," he said.
The FBI is now working closely with the Central Intelligence Agency and exchanging information with the National Security Agency, the Defense Intelligence Agency and counterparts in other countries - and Mueller said the cooperation is working.
"We are doing a much better job at integrating that intelligence and acting on that intelligence any place in the world," he said.
Mueller refused to discuss the National Security Agency's contentious electronic eavesdropping on people in the United States whose calls and e-mails U.S. President George W. Bush's administration believes involve the al-Qaida terror network - or comment on unidentified FBI officials who have been quoted as saying the program has not been very productive.
"The most I'll say is there are a number of programs - I'm not going to talk about specific programs - that have been helpful to securing the United States," the FBI chief said.
Last month, U.S. law enforcement officials confirmed that a classified radiation-monitoring program, conducted without warrants, targeted private U.S. property in Seattle and other cities in an effort to prevent an al-Qaida attack. The officials said the air monitoring took place from publicly accessible areas - which they said made warrants and court orders unnecessary.
Mueller refused to give any details, but said when the United States gets information about threats in particular cities "that talk about specific mechanisms that might be used ... we move to assure that the threat is not credible."
"We will use passive ... detectors to see if we pick up anything that might cause us concern, he said, emphasizing the word passive, "in the sense that it does not go through walls or anything like that but analyzes the environment to ensure that there isn't a dangerous substance," he said.
A U.S. official, speak on condition of anonymity because of the sensitivity of the issue, said the detectors seek evidence of chemical, biological or nuclear material and occasionally they have gotten "hits"_ all of which proved groundless.
Mueller vehemently denied that the United States, which has been seen as a guardian of human rights, was giving up the right to privacy in exchange for security.