Donald Trump says he will bring "peace through strength," reviving a time-tested phrase, but whether he is pursuing a strategy or just relying on a catchphrase is a matter of dispute.

In invoking "peace through strength," the incoming president appears to be likening himself to Ronald Reagan, who sharply raised military spending before negotiating, late in his 1981-89 presidency, with a newly reform-minded Soviet Union.

Henry Kissinger, the apostle of the cool-minded pursuit of national interests known as realpolitik, had also spoken of "peace through strength," but the idea has much deeper roots.