'Top Gun' inspiration becomes highest-ranking woman at PentagonPresident Barack Obama appointed Christine Fox as acting deputy defense secretary Tuesday, making the civilian analyst — who inspired Kelly McGillis' character in "Top Gun" — the highest-ranking woman ever at the Pentagon.

Fox replaces Ashton Carter, who is stepping down Wednesday. Fox, who had been director of cost controls at the Pentagon before she left for the academic world over the summer, has remained an unpaid consultant to Carter since then.

Defense Secretary Chuck Hagel said Fox would serve "pending the nomination and confirmation of a permanent successor" as his top deputy — an acknowledgment that Senate Republicans could stall the permanent nomination over the so-called nuclear option, the new rules put in place by Democrats to speed up approval of judicial appointments.

In a statement, Hagel called Fox "a brilliant defense thinker and proven manager" who "knows the intricacies of the Department's budget, programs and global operations better than anyone."

A senior defense official told NBC News that Fox would be able to "hit the ground running like no one else can."

"Simply put, no one knows the issues as well as Christine," the official said