Evidence has surfaced tying the top U.S. commander in Afghanistan to a sex scandal that led the head of the U.S. Central Intelligence Agency to step down.

The Defense Department announced on Tuesday that Marine Corps General John Allen, who is the commander of the International Security Assistance Force (ISAF) in Afghanistan, is currently being investigated for exchanging inappropriate e-mails with Jill Kelley who first tipped off the FBI about the extramarital affair of General David Petraeus, who served as Director of the Central Intelligence Agency (CIA) up until last Friday.

Kelley turned to the FBI after she got threatening e-mails from Petraeus’s lover Paula Broadwell.

General Allen reportedly was found to have exchanged with Kelley e-mails and documents amounting to some 30-thousand pages in the past two years.

At the White House, spokesman Jay Carney said “the president thinks very highly of General Allen,” while adding that Allen’s recent nomination to become NATO's Supreme Allied Commander has been delayed at the request of Defense Secretary Leon Panetta pending the investigation’s outcome.