It's been so long since we've seen what leadership looks like that its arrival can only come with a jolt.

President Trump's defense secretary, Gen. James Mattis, delivered the goods with his dazzling quote advising America's adversaries that he was their problem, not their worrywart.

"What keeps you awake at night?" CBS "Face the Nation" host John Dickerson asked Mattis.

"Nothing," a stonefaced Mattis responded. "I keep other people awake at night."

Simple, spontaneous, and effective.  It's strong evidence that the U.S. is back as a leader on the world stage.  The words are the antithesis of passive, and indicate an active orientation.  The U.S. no longer waits for problems to occur; it seeks them out and hunts them down before our enemies know that the U.S. is looking for them.

It's also reminiscent of General George Patton's smart statement that the purpose of war isn't to die for one's country, but to get the other SOB to die for his.  This isn't surprising, given Mattis's known interest in military history.

In any case, it signals the end of the Obama era's "leading from behind" policy.  This is clearly leading from the front.