(a) National security

Gov. Chris Christie recently challenged Sen. Rand Paul over his opposition to the National Security Agency (NSA) metadata program. Paul has also tangled with Sen. John McCain and other internationalists over drone warfare, democracy promotion and, more generally, intervention abroad.

So what else is new? The return of the most venerable strain of conservative foreign policy — isolationism — was utterly predictable. Isolationists dominated the party until Pearl Harbor and then acquiesced to an activist internationalism during the Cold War because of a fierce detestation of communism.

With communism gone, the conservative coalition should have fractured long ago. This was delayed by Sept. 11 and the rise of radical Islam. But now, 12 years into that era — after Afghanistan and Iraq, after drone wars and the NSA revelations — the natural tension between isolationist and internationalist tendencies has resurfaced.