With all the shouting it was easy to miss, but something new happened in Washington this week. If you can't see it yet, put yourself back in 2006, when everything about a Somali-American, Muslim congresswoman tweeting a line from a Puff Daddy song—as Minnesota Representative Ilhan Omar did Sunday evening—would have been unthinkable.

In March 2006, two established, neo-realist foreign policy wonks named John Mearsheimer and Stephen Walt published an article in the London Review of Books. They argued that outsized U.S. support for Israel, which receives more U.S. military aid than any other country on the planet, made little sense in a post–Cold War context in which Israel was no longer a "vital strategic asset." Mearsheimer and Walt attributed the irrational persistence of this policy to highly effective lobbying efforts "to steer US foreign policy in a pro-Israel direction."