The state of the Trump Presidency has been perpetual turbulence, which seems to be how the principal likes it. The latest vortex is over Mr. Trump’s disclosure of sensitive intel to the Russians—and whatever the particulars of the incident, the danger is that Presidencies can withstand only so much turbulence before they come apart.

The Washington Post reported Monday night that in an Oval Office meeting last week Mr. Trump relayed high-level “code word” classified material obtained from an ally to Russian Foreign Minister...