“The opportunity to get his views is very important,” Democratic Sen. Dianne Feinstein of California, chairwoman of the Senate Intelligence Committee, said of Petraeus.

CNN reported that Petraeus told one of its reporters in a conversation that his resignation had nothing to do with the Benghazi attack and that he wanted to testify.

Panetta’s order to Army Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, for the ethical standards review by the service chiefs was announced during a visit by the defense secretary to Bangkok, Thailand.

The assessment “is intended to reinforce and strengthen the standards that keep the military well led and disciplined,” Pentagon spokesman George Little said. “The secretary believes that the vast majority of our senior military officers exemplify the strength of character and the highest ethical standards the American people expect of those whose job it is to provide for the security of our nation.”

The review’s findings will be used as the basis for a report that will be presented to President Barack Obama by Dec. 1.

Some independent experts welcomed the announcement in light of the scandal enmeshing Petraeus and Allen, who is the top U.S. commander in Afghanistan.

“These are people who in their leadership role are supposed to set an example,” said Nicholas Fotion, a professor of philosophy and military ethics at Emory University in Atlanta. “If they don’t do that, they do more harm than if an ordinary male soldier has an affair with a female soldier. If you accept a leadership role, you accept certain responsibilities.”

Petraeus and other U.S. military leaders have been “glorified” by the American public during more than a decade of war, and some may have come to believe that they could relax their standards of conduct, he said.

“The high status we gave them has gone to their heads,” said Fotion.

Frances V. Harbour, a professor of international security issues at George Mason University in Virginia who specializes in military ethics, said that the new review appeared to be aimed at reinforcing at senior levels lessons in “making the right choices” that military academies work to inculcate in cadets.

She said that the pressures from long overseas deployments away from families to which service members have been subjected is “part of the explanation” for troubling behavior by senior officers. “But that doesn’t mean it’s an excuse,” she added.

“You are still obligated by the special promises you made to not just follow normal moral codes, but to follow these military codes which are much stricter,” she said.

Petraeus, 60, who has been married for 38 years, disclosed his affair with Broadwell, his married biographer, in resigning on Friday, saying his behavior was “unacceptable.”

On Monday, Panetta announced that he’d ordered the Pentagon inspector general to investigate more than 20,000 emails and other documents that Allen exchanged with Jill Kelley, a Tampa, Fla., socialite who threw parties for prominent citizens and senior officers from MacDill Air Force Base, home of the U.S. Central Command.

Kelley, 37, and her husband were friends with Petraeus – who served as CENTCOM commander from October 2008 until June 2010 – and Allen, 58, who served as Petraeus’ deputy, and his wife.

Kelley’s complaint earlier this year to an FBI agent who she knew about threatening anonymous emails triggered the FBI investigation that led to Broadwell and uncovered her affair with Petraeus. The first email reportedly was sent in May to Allen, who subsequently forwarded it to Kelley.

The military also has been rocked by Panetta’s decision this week to penalize William Ward, a former four-star general who led U.S. Africa Command, and order him to repay $82,000 for taking extravagant and unauthorized trips with his wife, and the sexual assault and adultery charges facing Brig. Gen. Jeffrey Sinclair of the 82nd Airborne Division.

In another recent case, James H. Johnson III, a former commander of the 173rd Airborne Brigade, was convicted of bigamy and fraud stemming from an improper relationship with an Iraqi woman and her family, busted in rank and expelled from the Army.

Greg Gordon of the Washington Bureau contributed.