President Barack Obama has tapped White House homeland security adviser John Brennan as his nominee to lead the Central Intelligence Agency.

Obama on Monday appeared with Brennan in the East Room of the White House to name him as his pick to succeed former CIA chief David Petraeus, who resigned in November after admitting to an affair with his biographer.

Brennan is a 25-year veteran of the CIA and among Obama's closest advisers. Obama called him a friend.

The president praised Brennan as one of the most skilled and respected intelligence professionals. Obama says Brennan and former Sen. Chuck Hagel, whom the president nominated to lead the Pentagon at the same event, understand that "the work of protecting our nation is never done."

Brennan's post requires Senate confirmation.