What did Donald Trump do today?

He tried to take revenge on Nancy Pelosi.

Minutes before members of Congress departed on a planned trip to NATO headquarters in Belgium and then Afghanistan, Trump canceled their military transport. In a letter to House Speaker Nancy Pelosi, Trump said the "excursion" was inappropriate during a government shutdown.

The tone of the letter made it clear that Trump was trying to retaliate against Pelosi for her suggestion that because of the security logistics involved, the televised State of the Union address should not happen in the House chamber during the shutdown. 

But regardless of its intent, the letter is revealing about what Trump does or doesn't know.

Trump sneeringly suggested that Pelosi could take a commercial flight instead. In fact, as Speaker and second in the line of succession to the presidency, she cannot, because of security rules put in place after the September 11th attacks. By revealing the secret details of the trip before it was underway, Trump essentially made it impossible for any member of Congress to go.

Trump also scoffed at the very idea of visiting troops and military commanders in a war zone, during a shutdown, calling it a "public relations event." Trump visited troops and military commanders in Iraq during this same shutdown. 

Trump has been furious over the political beating he is taking during the shutdown, which is beginning to erode his support among the "base" voters he is trying to rally in the first place. But his anger, and his sabotage of Congress's travel, may also be due to his own inability to leave the White House because of the political optics. Trump has been forced to spend almost every night since late November away from his winter resort home at Mar-a-Lago, where he normally spends two or three nights a week.

Trump's wife Melania took a military transport to Mar-a-Lago today.

So what?

• The president isn't supposed to actively prevent other branches of government from doing their jobs.

• A president who was reportedly too afraid to travel to a war zone for the first two years of his term should probably have a better understanding of the security implications.

• Even by Trump's standards, this is petty.