The anniversary of the Sept. 11, 2001 terrorist attacks looms large in the minds of all Americans, and most intently, of course, among those working in the agencies charged with protecting the country from additional attacks including any that may be timed to coincide with the one-year anniversary.

Thus, it's to be expected and is appreciated that the FBI, among other agencies, is operating in a state of heightened alert.

Indeed, just moments ago, the Office of Homeland Security raised the threat level from "elevated" to "high," or more directly, from "yellow" to "orange," the first increase since March.

According to CNN's broadcast, the increase was sparked by a specific threat to a target overseas, but that target has not been disclosed.

The administration, through the FBI, has indicated that intelligence gathering activities have picked up a substantial increase in ominous "chatter" in recent days.

"A large volume of threats of undetermined reliability continues to be received and investigated by the FBI," according to a bulletin posted on the agency's web site.

"Several of these threats make reference to the events of Sept. 11, 2001, and to New York City and Washington, D.C."

A report this morning from the Associated Press indicates that multiple sources are being pursued by federal authorities.

"The warnings are based on information from all U.S. intelligence sources, from telephone calls to interviews with detainees at the U.S. Naval Base in Guantanamo Bay, Cuba, according to a senior law enforcement official," writes the A.P.'s Christopher Newton.

"Information from detainees, most of whom have been out of circulation for months, has proven [sic] false before. U.S. officials have said they act on it only when corroborated through multiple sources, but believe advising caution still is necessary," according to the A.P.

It's surprising to see plainly out-of-the-loop Guantanamo detainees listed as sources regarding potential threats, given that they have yet to provide information leading to the capture of even a single Al Queda operative for involvement in terrorist attacks that already have occurred.

A cynic might say that "interviews with detainees," to the extent they are deemed part of a credible strategy by the public, lend an element of support to the Bush administration's grossly expanded powers to arrest, imprison, and confine incommunicado pretty much anyone, including American citizens, on suspicion of, well, pretty much anything.