A top U.S. military officer in Afghanistan is under scrutiny for allegedly ordering the illegal use of "psychological operations" against American dignitaries during official visits to the country last year.
Among the visiting officials who may have been targeted by "psy-ops" was Chairman of the Joint Chiefs Adm. Mike Mullen.
Lt. Gen. William Caldwell, who heads the effort to train Afghan forces, instructed subordinates to use tactics reserved exclusively to target the enemy, sources familiar with the situation told Rolling Stone magazine.
Caldwell reportedly sought to pressure U.S. senators and congressmen and other VIPs to provide more troops and funding for the war.
Gen. David Petraeus, commander of U.S. forces in Afghanistan, said he was preparing to open an investigation "to determine the facts and circumstances surrounding the issue."
Defense Secretary Robert Gates said in a statement that he supports Petraeus' decision, and cautioned against reaching conclusions about Caldwell's behavior before the Pentagon had established the facts.
Caldwell "categorically denies" the allegations, a spokesman told Rolling Stone.
The magazine report is based largely on the account of a reservist with the Texas National Guard, Lt. Colonel Michael Holmes, who lead the information operations unit in Kabul.
"My job in psy-ops is to play with people's heads, to get the enemy to behave the way we want them to behave," Holmes is quoted as saying. "I'm prohibited from doing that to our own people. When you ask me to try to use these skills on senators and congressmen, you're crossing a line."
Holmes said he was told to focus exclusively on a "deeper analysis of pressure points we could use to leverage the delegation for more funds."
The so-called "IO" unit compiled detailed research on the backgrounds of visiting dignitaries and honed Caldwell's presentations to be as compelling as possible, according to Holmes, who says he tried to resist Caldwell's orders and later reported them to superiors.
Federal law prohibits government use of propaganda techniques, including psychological tactics, on U.S. citizens.
The lawmakers allegedly targeted by the campaign include Arizona Sen. John McCain, Rhode Island Sen. Jack Reed, Michigan Sen. Carl Levin, and Minnesota Sen. Al Franken.
The psy-ops team also may have targeted the Czech ambassador to Afghanistan and the German interior minister, according to documents obtained by the magazine.
"Charges of this nature are very serious and disturbing and have to be fully investigated," Reed said in an interview on MSNBC.
But he and other senators mentioned in the article insisted they were not swayed by any single briefing or encounter during a visit to Afghanistan.
"I try to get a broad view and not to put too much stake in any one position while I travel," said Reed, an Army veteran who served in Vietnam and who's been to Afghanistan 11 times.
"I knew that I would have to crosscheck their [Caldwell's team] assessment by talking to other military officials, diplomatic officials, outside experts and troops in the field," said Franken of his most recent visit. "I always raise skeptical questions when discussing this topic."
"For years, I have strongly and repeatedly advocated for building up Afghan military capability because I believe only the Afghans can truly secure their nation's future. I have never needed any convincing on this point," said Levin. "I am confident that the chain of command will review any allegation that information operations have been improperly used in Afghanistan."
The latest Rolling Stone article, entitled "Another Runaway General," follows a June expose by the magazine that resulted in the resignation of the top U.S. military officer in Afghanistan, Gen. Stanley McChrystal.
ABC News' Luis Martinez and Matthew Jaffe contributed to this report.