US Defence Secretary Leon Panetta has warned against jumping to conclusions over the top US commander in Afghanistan, who has been drawn into a widening scandal that already has cost CIA Director David Petraeus his job.
Marine General John Allen, who denies any wrongdoing, is being investigated for potentially inappropriate communications with a woman at the centre of the Petraeus case, Jill Kelley, a Florida socialite.
Panetta defended his decision to refer the case to the Pentagon's inspector general and for yesterday suspending Allen's nomination to another top position in the US military, saying it was a prudent step "until we determine what the facts are".
At the same time, he praised Allen's work commanding the Afghan war effort, a position he retains despite the probe.
"No one should leap to any conclusions here. General Allen is doing an excellent job at ISAF, in leading those forces," Panetta said, referring to the NATO-led force.
"He certainly has my continued confidence to lead our forces and continue the fight."
Defence officials and people close to Petraeus say neither he nor Allen had a romantic relationship with 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 Petraeus' biographer, Paula Broadwell, who sent Kelley a series of anonymous, harassing emails which touched off an investigation that uncovered evidence of an affair between Petraeus and 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.
Kelley had gotten to know both Petraeus and Allen as a volunteer setting up social events at MacDill Air Force Base outside Tampa, headquarters of US Central Command.
The relationship was evidently close enough that both men intervened in a child custody battle involving 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," Allen wrote about Khawam in a September 22 letter to a Washington, DC, court.
Allen and Kelley communicated often enough over the past two years to produce between 20,000 and 30,000 pages of email and other messages, which were turned over to Defence Department investigators on Sunday.
The actual volume of communications is likely much smaller, an official said, as the printouts include messages involving other people and email threads including prior communications.
A senior defence official said 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 US 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.
Allen has denied that the two had a sexual relationship. Adultery can lead to a dishonorable discharge under US military law.
The scandal complicates President Barack Obama's efforts to reorganise his national security team following his re-election. The White House said it still had faith in Allen, but acknowledged its plans to transfer him to Europe, where he would head US and allied forces, have been suspended.
Obama also has to find a replacement for Petraeus at the CIA at a time when the president is vetting candidates to head the State and Defense departments.
The scandal could throw a wrench into Obama's relations with Congress at a time when he is engaging in high-stakes budget negotiations to avoid the combination of tax increases and spending cuts known as the "fiscal cliff."
"I certainly wouldn't call it welcome," White House spokesman Jay Carney said of the scandal.
Both Allen and the official due to replace him in Afghanistan, Marine Corps General Joseph Dunford, must be confirmed by the US Senate before they can take up their new posts.