WASHINGTON -- Gen. David Petraeus officially takes over U.S. Central Command on Friday.

Petraeus took the reins of U.S. Central Command from acting commander Army Lt. Gen. Martin Dempsey in a ceremony in Washington, with Defense Secretary Robert M. Gates presiding over the change of command.

"Gen. Petraeus, you are again taking responsibility for our precious sons and daughters," Gates said. "I have no doubt they will continue to make you and me -- indeed, all Americans -- very proud."

After helping to calm things in Iraq, the general will still have oversight over that war. He is also in charge of overseeing things in the rest of the Middle East, including Afghanistan, where American fortunes appear darker.

The promotion also puts him at the forefront of U.S. efforts to deal with Pakistan, an ally in the war on terror as well as a country threatened with financial ruin, torn by an insurgency and armed with nuclear weapons.

His greatest challenge could come from Pakistan.

Gates addressed the challenges before Petraeus. "A few weeks ago, I said that history will regard him as one of our nation's great battle captains," Gates said. "He is the pre-eminent soldier-scholar-statesman of his generation, and precisely the man we need in this command at this time."

Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, said in June that any future terrorist attack on the U.S. would probably originate in Pakistan's western tribal regions.

But Pakistan has long maintained the pursuit of any terrorists inside its borders will be handled by its own military.

A Pakistani official confided that a more comprehensive strategy is in the works. He said it will include U.S. cooperation, but it will be led by Pakistan.