What did Donald Trump do today?

He thought a threat by North Korea was a compliment.

Trump was once again "confined" to the White House today by the government shutdown, now in its 11th day. And once again he spent most of the day (including the early morning hours) tweeting. Most of them were angry or defensive—they included sarcastic all-caps holiday greetings to his "HATERS," and calling a retired Army general a "dog"—but one of them offered what Trump apparently thought was good news.

Trump apparently took what virtually everyone else saw as a threat or a warning and concluded that Kim Jong-un was praising him. 

In reality, what Kim said was that North Korea would not make or test nuclear weapons unless the United States dropped its economic sanctions. Those sanctions are essentially the only thing besides the threat of nuclear annihilation that has kept the Kim regime in check until now. 

Basically, Trump was bragging that by "falling in love" with Kim Jong-un and agreeing to weaken the U.S.-South Korea military alliance, he had succeeded in getting North Korea to do exactly what it has been doing all along.

North Korea already has a stockpile of perhaps 60 nuclear warheads. Kim did not promise to give up this arsenal (and never has). He only suggested that he would not add to it, but warned that

if the United States does not deliver its promise and misjudge our people’s patience, making unilateral demands to continue sanctions and put pressure on us, we will have no choice but to seek a new path to protect the country’s independence, interests and peace on the Korean Peninsula.

Kim has had Trump over a barrel politically since Trump went against the strenuous advice of his advisors and accepted Kim's invitation to a summit meeting. By declaring the summit a success even before it had happened, and by insisting immediately afterwards that North Korea was "no longer a nuclear threat," Trump gave Kim an enormous amount of leverage over his presidency. To even hint that North Korea was not acting in good faith would be to admit failure, something Trump seems incapable of even if he could afford it politically. This is, at least in part, why Trump has ignored his own intelligence agencies' findings that the Kim regime is accelerating work on their missile program and is developing plans to hide its nuclear stockpile from inspectors.

Why is this a problem I should care about?

• No president can afford to be this incompetent where the nuclear security of the United States and its allies are concerned.

• It's a problem when a president flies into a rage at a retired American military officer who criticizes him, and then "looks forward" to spending more time with a murdering, torturing dictator.

• Good "dealmakers" don't get nothing in exchange for something, and aren't pleased with themselves when that happens.