The top American general in Afghanistan has been cleared of misconduct by the Pentagon for emails sent to a socialite.
General John Allen's nomination as head of NATO forces in Europe had been put on hold amid reports that the emails were inappropriate.
Harassment complaints by Florida socialite Jill Kelley led the FBI to unmask an affair between CIA chief David Petraeus and his biographer Paula Broadwell. He later resigned, the BBC reports.
Defence Secretary Leon Panetta has welcomed the investigation's conclusion that General Allen had not broken any military rules against conduct unbecoming an officer.
General Allen had been President Barack Obama's choice as the next US commander of NATO forces in Europe and is due to relinquish command in Afghanistan in February this year.
The emails first came to light as part of a wider investigation into email harassment against Mrs Kelley, who knew both General Allen and Mr Petraeus, a former general, through social contacts on the Florida army base where US Central Command is headquartered.
Earlier reports suggested that the general exchanged thousands of emails, some described as inappropriate and flirtatious, with Mrs Kelley. The Afghanistan commander had also written a letter to a judge in support of Mrs Kelley's twin sister in a messy custody dispute.
Defence officials told the Washington Post that the full investigation had shown that there were in fact only several hundred emails exchanged between the two, mostly notes on current news topics, social invites or compliments on General Allen's television interviews.
"Some of the messages are not the sort of things you would print in a family newspaper," the official said. "But that doesn't mean he violated military regulations by sending and receiving them."
In addition to the inquiry into General Allen, Mr Panetta asked the Joint Chiefs of Staff to review ethics training after a series of misconduct cases.
General Martin Dempsey, chairman of the Joint Chiefs, has not released the results of his review but has said he found that ethics training for senior leaders should begin earlier in an officer's career and be reinforced more frequently.
