WASHINGTON -- The Pentagon has been using a little-known power to obtain banking and credit records of hundreds of Americans and others suspected of terrorism or espionage inside the United States, part of an aggressive expansion by the military into domestic intelligence gathering.
The CIA has also been issuing what are known as national security letters to gain access to financial records from American companies, though it has done so only rarely, intelligence officials say.
Banks, credit card companies and other financial institutions receiving the letters have usually turned over documents voluntarily, allowing investigators to examine the financial assets and transactions of U.S. military personnel and civilians, officials say.
The FBI, the lead agency on domestic counterterrorism and espionage, has issued thousands of national security letters since the attacks of Sept. 11, provoking criticism and court challenges from civil liberties advocates who see them as unjustified intrusions into Americans' private lives.
But it was not previously known, even to some senior counterterrorism officials, that the Pentagon and the CIA have been using their own "noncompulsory" versions of the letters. Congress has rejected several attempts by the two agencies since 2001 for authority to issue mandatory letters, in part because of concerns about the dangers of expanding their role in domestic spying.
The military and the CIA have long been restricted in their domestic intelligence operations, and both are barred from conducting traditional domestic law enforcement work. The CIA's role within the United States has been largely limited to recruiting people to spy on foreign countries.
Carl Kropf, a spokesman for the director of national intelligence, said intelligence agencies like the CIA used the letters on only a "limited basis."
Pentagon officials defended the letters as valuable tools and said they were part of a broader strategy since the Sept. 11 attacks to use more aggressive intelligence-gathering tactics - a priority of former Defense Secretary Donald H. Rumsfeld. The letters "provide tremendous leads to follow and often with which to corroborate other evidence in the context of counterespionage and counterterrorism," said Maj. Patrick Ryder, a Pentagon spokesman.
Government lawyers say the legal authority for the Pentagon and the CIA to use national security letters in gathering domestic records dates back nearly three decades and, by their reading, was strengthened by the anti-terrorism law known as the USA Patriot Act.
Pentagon officials said they used the letters to follow up on a variety of intelligence tips or leads. While they would not provide details about specific cases, military intelligence officials with knowledge of them said the military had issued the letters to collect financial records regarding a government contractor with unexplained wealth, for example, and a chaplain at Guantanamo Bay erroneously suspected of aiding prisoners at the facility.
Usually, the financial documents collected through the letters do not establish any links to espionage or terrorism and seldom have led to criminal charges, military officials say. Instead, the letters often help eliminate suspects.
"We may find out this person has unexplained wealth for reasons that have nothing to do with being a spy, in which case we're out of it," said Thomas A. Gandy, a senior Army counterintelligence official.
But even when the initial suspicions are unproven, the documents have intelligence value, military officials say.
In the next year, they plan to incorporate the records into a database at the Counterintelligence Field Activity office at the Pentagon to track possible threats against the military, Pentagon officials said. Like others interviewed, they would speak only on the condition of anonymity.
Military intelligence officers have sent letters in up to 500 investigations over the past five years, two officials estimated. The number of letters is likely to be well into the thousands, the officials said, because a single case often generates letters to multiple financial institutions. For its part, the CIA issues a handful of national security letters each year, agency officials said. Congressional officials said members of the House and Senate Intelligence Committees had been briefed on the use of the letters by the military and CIA.
Some national security experts and civil liberties advocates are troubled by the CIA and military taking on domestic intelligence activities, particularly in light of recent disclosures that the Counterintelligence Field Activity office had maintained files on Iraq war protesters in the United States in violation of the military's own guidelines. Some experts say the Pentagon has adopted an overly expansive view of its domestic role under the guise of "force protection," or efforts to guard military installations.
"There's a strong tradition of not using our military for domestic law enforcement," said Elizabeth Rindskopf Parker, a former general counsel at both the National Security Agency and the CIA who is dean at the McGeorge School of Law at the University of the Pacific. "They're moving into territory where historically they have not been authorized or presumed to be operating."
Similarly, A. John Radsan, an assistant general counsel at the CIA from 2002 to 2004 and now a law professor at William Mitchell College of Law in St. Paul, Minn., said: "The CIA is not supposed to have any law enforcement powers, or internal security functions, so if they've been issuing their own national security letters, they better be able to explain how they don't cross the line."
The Pentagon's expanded intelligence-gathering role, in particular, has created occasional conflicts with other federal agencies. Pentagon efforts to post U.S. military officers at embassies overseas to gather intelligence for counterterrorism operations or future war plans have rankled some State Department and CIA officials, who see the military teams as duplicating and potentially interfering with the intelligence agency.
In the United States, the FBI has complained about military officials dealing directly with local police - rather than through the bureau - for assistance in responding to possible threats against a military base. FBI officials say the threats have often turned out to be uncorroborated and, at times, have stirred needless anxiety.
The military's frequent use of national security letters has sometimes caused concerns from the businesses receiving them, a counterterrorism official said. Lawyers at financial institutions, which routinely provide records to the FBI in law enforcement investigations, have contacted bureau officials to say they were confused by the scope of the military's requests and whether they were obligated to turn the records over, the official said.
Companies are not eager to turn over sensitive financial data about customers to the government, the official said, "so the more this is done, and the more poorly it's done, the more pushback there is for the FBI."
The bureau has frequently relied on the letters in recent years to gather telephone and Internet logs, financial information and other records in terrorism investigations, serving more than 9,000 letters in 2005, according to a Justice Department tally. As an investigative tool, the letters present relatively few hurdles; they can be authorized by supervisors rather than a court.
Passage of the Patriot Act in October 2001 lowered the standard for issuing the letters, requiring only that the documents sought be "relevant" to an investigation and allowing records requests for more peripheral figures, not just targets of an inquiry.
Some Democrats have accused the FBI of using the letters for fishing expeditions, and the American Civil Liberties Union won court challenges in two cases, one for library records in Connecticut and the other for Internet records in New York. Concerned about possible abuses, Congress imposed new safeguards in extending the Patriot Act last year, in part by making clear that recipients of national security letters could contact a lawyer and seek court review.
Unlike the FBI, the military and the CIA do not have wide-ranging authority to seek records on Americans in intelligence investigations. But the expanded use of national security letters has enabled the Pentagon and the intelligence agency to collect records on their own. Sometimes, military or CIA officials work with the FBI to seek records, as occurred with an American translator who had worked for the military in Iraq and was suspected of having ties to insurgents.
After the Sept. 11 attacks, Rumsfeld directed military lawyers and intelligence officials to examine their legal authority to collect intelligence both inside the United States and abroad. They concluded that the Pentagon had "way more" legal tools than it had been using, a senior Defense Department official said.
Military officials say the Right to Financial Privacy Act of 1978, which establishes procedures for government access to sensitive banking data, first authorized them to issue national security letters.
While the letters typically have been used to trace the financial transactions of military personnel, they also have been used to investigate civilian contractors and people with no military ties who might pose a threat to the military, officials said. Military officials say they regard the letters as one of the least intrusive means to gather evidence. When a full investigation is opened, one official said, it has now become "standard practice" to issue such letters.
One prominent case in which letters were used to obtain financial records, according to two military officials, was that of a Muslim chaplain at Guantanamo Bay, Cuba, who was suspected in 2003 of aiding terror suspects imprisoned at the facility. The espionage case against the chaplain, James J. Yee, soon collapsed. He was convicted on lesser charges of adultery and downloading pornography and received a written reprimand. But after Yee appealed, a senior officer overturned the convictions and the reprimand was withdrawn.
Eugene Fidell, a military law expert and a defense lawyer for the former chaplain, said he was unaware that military investigators might have used national security letters to obtain financial information about Yee, nor was he aware that the military had ever claimed the authority to issue the letters.
Fidell said he found the practice "disturbing," in part because the military does not have the same checks and balances when it comes to Americans' civil rights as does the FBI.
"Where is the accountability?" he asked. "That's the evil of it - it doesn't leave fingerprints."