The scandal that felled CIA director David Petraeus widened on Tuesday to ensnare the top U.S. commander in Afghanistan, Marine General John Allen, who was being investigated for "flirtatious" communications with a woman at the centre of the case.
Though a law-enforcement probe has not uncovered any evidence so far of legal wrongdoing or security risks, it does raise questions about the unusually close relationship between a Florida socialite, her sister and two of the most powerful men in the national-security apparatus of the United States.
The woman in question, Jill Kelley, has emerged as a central figure in the scandal that has brought down one of the most admired military leaders in the United States and threatens to derail the career of another.
Defence officials and people close to Mr. Petraeus say neither he nor Gen. Allen had a romantic relationship with Ms. Kelley, a 37-year-old wife and mother, who is described as a prominent presence in military circles in Tampa.
She may have been seen as a rival by Mr. Petraeus's biographer, Paula Broadwell, who sent Ms. Kelley a series of anonymous, harassing e-mails that touched off an investigation that uncovered evidence of an affair between Mr. Petraeus and Ms. Broadwell.
According to law-enforcement sources, FBI investigators decided to pursue the matter when they found the messages contained information about the CIA chief's activities that was not publicly available.
Ms. Kelley had gotten to know both Mr. Petraeus and Gen. Allen as a volunteer setting up social events at MacDill Air Force Base outside Tampa, headquarters of U.S. Central Command.
The relationship was evidently close enough that both men intervened in a child-custody battle involving Ms. Kelley's twin sister, Natalie Khawam.
"She is a dedicated mother, whose only focus is to provide the necessary support, love and care for her son," Gen. Allen wrote about Ms. Khawam in a Sept. 22 letter to a Washington court.
Gen. Allen and Ms. Kelley communicated often enough over the past two years to produce between 20,000 and 30,000 pages of e-mail and other messages, which were turned over to Defence Department investigators on Sunday.
A senior Defence official told Reuters the messages were seen as inappropriate because they were "flirtatious" in nature, not because they dealt with sensitive information.
But "flirtatious" may be an understatement. Another U.S. official said the Pentagon only decided to refer it for investigation after an initial look found the communications to be of "a sufficient character" to warrant further review.
Gen. Allen has denied that the two had a sexual relationship, officials said on condition of anonymity. Adultery can lead to a dishonourable discharge under U.S. military law.
The scandal complicates President Barack Obama's efforts to reorganize his national-security team following his re-election. The White House said it still had faith in Gen. Allen, but its plans to transfer him to Europe as NATO's top military commander have been suspended.
Mr. Obama also has to find a replacement for Mr. Petraeus at the CIA at a time when the President is vetting candidates to head the State and Defence departments.
"I certainly wouldn't call it welcome," White House spokesman Jay Carney said of the scandal.
Defence Secretary Leon Panetta said Gen. Allen, a four-star general, would stay in his job for the time being, and the White House said Mr. Obama still had confidence in Gen. Allen's ability to command the 68,000 U.S. troops in Afghanistan.
Both Gen. Allen and the official due to replace him in Afghanistan, Marine Corps General Joseph Dunford, must be confirmed by the U.S. Senate before they can take up their new posts in February.
Lawmakers on the Senate armed services committee said they would go ahead with a confirmation hearing for Gen. Dunford on Thursday. Gen. Allen's appearance was cancelled.
A senior lawmaker said on Tuesday the Senate intelligence committee still wanted to talk to Mr. Petraeus about the CIA's role in events surrounding the September attack on the U.S. consulate in Benghazi, Libya.
"The committee will talk to him; the committee thinks it's important," said Senator Dianne Feinstein, the panel's Democratic chairwoman. "The actual time of it is undecided at this point."
FBI agents searched Ms. Broadwell's home in Charlotte, N.C., late Monday in a sign that the case involving Mr. Petraeus was not fully closed.
Agents entered the house carrying boxes at around 9 p.m. and emerged four hours later, carrying away what appeared to be two computers and about 10 boxes. Ms. Broadwell's family was not at home at the time.
From our community:
We asked military members whether they think the military holds them to impossible standards when it comes to their personal life. Here are some of their responses:
"The responsibility and nature of our commitment necessitates an extremely high standard. Is it impossible to maintain? No, but if you can't maintain it, it is a volunteer force and you should retire." Keith Yamashita, retired colonel
"Impossible and outrageous standards for everything for those gallant men and women who put their lives on the line for us. We retire and ignore anyone who is having mental problems after traumatic events in the line of duty; pay them a poor pension; and do nothing for the marital problems that are so much a part of service away from family." Elliot Leyton, retired lieutenant