WASHINGTON — As Americans consider whether they are more safe or less five years after the Sept. 11 attacks, one thing is certain: They are being monitored by their own government in ways unforeseen before terrorists flew planes into the World Trade Center and Pentagon.
Within minutes of the strikes, U.S. law enforcement and intelligence-gathering authorities mobilized to find the culprits and prevent another attack.
They increased the tapping of Americans' phone calls and voice mails. They watched Internet traffic and e-mails as never before. They tailed greater numbers of people and into places previously deemed off-limits, such as mosques.
They clandestinely accessed bank and credit card transactions and school records. They monitored travel. And they entered homes without notice, looking for signs of terrorist activity and copying the contents of entire file cabinets and computer hard drives.
Authorities even tried to get inside people's heads, using supercomputers and "predictive" software to analyze enormous amounts of personal data about them and their associates in an effort to foretell who might become a terrorist, and when.
In the five years since the attacks, the scope of domestic surveillance has steadily increased, according to interviews with dozens of current and former U.S. officials and privacy experts.
Some of these programs have been debated and approved by the courts and Congress -- the traditional checks against intrusions on Americans' privacy, protected under the 4th Amendment.
Others have not. Some of them are operating without the knowledge or approval of judicial and legislative overseers, officials and experts say.
Two such classified programs have been disclosed by the media, over the objections of the Bush administration. One involves the National Security Agency's warrantless wiretapping of suspicious phone calls and e-mails into and out of the United States. The other is an effort by the Treasury Department and the CIA to monitor international bank transfers.
Privacy experts and even some ranking lawmakers in Congress say their efforts to learn about other suspected surveillance efforts have been blocked.
They believe that some of the activity is so secret that none but a small circle of top administration officials and operational support personnel know about it -- though notification of congressional leaders is legally required.
"The White House simply refuses to be straight with us about what they're up to," said Sen. Ron Wyden (D-Ore.), who says he has pressed unsuccessfully for answers as a member of the Senate's Select Committee on Intelligence, which entitles him to classified briefings on the subject.
"My sense today is that there is a staggering amount of personal information being collected on millions of Americans," Wyden said. "And how it's accessed and how it's used is at best unclear. What is certain is that there is no real accountability to ensure that a balance is struck between fighting terrorism and protecting privacy."
In response, administration officials say that they have the authority to conduct whatever surveillance is underway, in part due to the special war powers granted to President Bush by Congress a week after the Sept. 11 attacks.
In a speech Thursday, Bush lobbied Congress for updated and expanded surveillance powers, saying they were needed to keep pace with a stealthy and technologically savvy enemy.
Meanwhile, the domestic surveillance effort continues within virtually every U.S. counter-terrorism, law enforcement and intelligence agency.
The programs comprise actual surveillance of Americans' activities and communications, and "dataveillance," the practice of mining the vast amounts of personal data compiled on Americans.
On both fronts, the NSA is leading the effort from its headquarters in Fort Meade, Md., just outside Washington.
For decades, the NSA's satellites and land-based listening posts have intercepted billions of phone calls and e-mails, searching for keywords that might suggest terrorist or criminal activity, espionage, or other efforts harmful to national security.
After Sept. 11 such activity increased dramatically, and has been aided by the cooperation of at least some phone and Internet companies that have granted access to their mammoth caches of digitized information, current and former U.S. officials and privacy experts say.
Robert L. Deitz, general counsel for the NSA, told Congress last week that the NSA's primary mission since Sept. 11 has been to develop ways of eavesdropping on Al Qaeda and other terrorist organizations that have used cutting-edge technologies to stay ahead of their pursuers.
The NSA has improved its ability to monitor the entire spectrum of communications, including fiber-optic and wireless transmissions, instant messages, BlackBerry e-mails and voice conversations sent over the Internet, officials and experts say.