What did Donald Trump do today?

He forgot about, or lied about, Mexico's own border control efforts.

The overall theme of Easter Sunday's tweetstorm was immigration. One of the claims Trump made was that "Mexico is doing very little, if not NOTHING, at stopping people from flowing into Mexico through their Southern Border, and then into the U.S."

In reality, Mexico's Programa Frontera Sur (Southern Border Program) prevents many would-be undocumented Central and South American immigrants to the United States from reaching their destinations. The program, adopted by Mexico under pressure from the Obama administration, is controversial: critics say that Mexican border officials violate the human rights of migrants they catch, and that the tactics make migrants vulnerable to exploitation by gangs operating in the area.

Nevertheless, it has prevented hundreds of thousands of people from traveling through Mexico to work in the United States--which is why Mexico has used the continuation of the program as leverage against Trump.

As with most false things Trump tweets out when away from the supervision of his staff, it's not clear whether he knew about Frontera Sur and lied, or was told and forgot, or never asked in the first place.

So what?

• A president who can't learn the truth about important policy issues is no better than a president who simply won't tell the truth about important policy issues.
  
• It's bad if the President of the United States has somehow given Mexico the upper hand in negotiations over border security.