Trump, briefed on highly sensitive info given the US by an outside agency on condition it would not be passed on to anyone without their OK, ignored all caveats and unexpectedly shared it with the Russian Foreign Minister and the Ambassador to the US, thrilled to show how cool it is to be president and what cool intelligence info he is privy to.
Why the latest White House crisis is a really big deal
As soon as they knew what he had done, White House officials scrambled to contact the CIA and NSA, hoping to minimize the damage.
The danger is the Russians can, from details provided by Trump, figure out the source, thus putting the source at risk, and that the outside agency that gave the info to the US government - and perhaps others, as well - will be reluctant to share in future.
It turns out that in many cases the best information available to the US relies on such outside agencies, sharing on just such conditions of secrecy.
Defiant Trump says he had 'absolute right' to share information with Russia
The president does indeed have the lawful right to do this, to declassify anything on the spot by sharing it, a right possessed by no one else in all the US government or all the wide world.
Technically, having declassified the info, it is now unclassified information for anybody at all to lawfully share with anybody at all.
No one has mentioned that unfortunate side-effect of the president's childish blurt, his foolish bragging, his showing-off to the Russians in his office.
They were there partly to please Vladimir Putin, who asked Trump to take this meeting during a phone call, and partly to stick a finger in the eye of people concerned about Trump's Russia connections one day after he fired the man chiefly responsible for running the FBI investigation of those connections.
Meanwhile, the blockhead in the White House who just leaked highly sensitive intelligence to the Russians has demanded people leaking embarrassing information from his White House be found and punished, right now.