“They’re truly frightened about him,” said Bruce Jentleson, a Duke University professor who served as a foreign policy aide in both the Obama and Clinton administrations. Noting that an inadvertent disclosure of classified information to Russian officials would demonstrate “incompetence, impetuousness” and “mania,” Jentleson added, “I’m scared, too.”

The refusal of Republicans to defend Trump in the wake of the Post story shows his support from partisan allies wearing thin. That’s damaging on its own to the president’s ability to achieve his agenda, among other consequences.

Moreover, it signals political problems that magnify chances for Democrats to regain control of the House of Representatives in 2018 mid-term elections. If they do, Trump would face a serious risk of impeachment proceedings, which a small number of Democratic lawmakers are already suggesting.

As with many controversies involving Trump, this one has provided more questions than answers. What makes it especially hazardous is that it involves a compromise of national security information involving both Moscow, for decades the foremost menace to the U.S., and ISIS, which Americans now see filling that role.

“Until we know what he actually shared, it’s a bit reckless to speculate,” said Jim Steinberg, a national security aide to the Obama and Clinton administration, about the Post story. “But with Trump, it’s possible the leaker deserves the Medal of Freedom.”