Donald J. Trump boasts among other things about his steel-trap memory. It’s the “best,” isn’t that right, Mr. President?

Well, the president put out a tweet today saying that — despite what he said on national TV a year ago — he didn’t fire FBI Director James Comey over the “Russia thing.”

Ohhh, no! His firing of Comey had to do with the Hillary Clinton email matter and the way the FBI was handling it — or so he says at this moment.

Hold on! He told NBC News’s Lester Holt a year ago that he canned Comey because of the investigation he was leading into whether the Trump campaign colluded with Russians who meddled in our 2016 presidential election.

And don’t you remember what Trump told Russian government visitors to the White House? He said he fired Comey because he is a “nut job” and because he wanted to take pressure off from the Russia probe.

In some circles that could be construed as an obstruction of justice. Hmm. Who knows? Maybe the special counsel appointed to examine the “Russia thing” will make that determination. Or … maybe not!

But the president’s penchant for tweeting these issues gives many of us pause to wonder: Does he know what he’s talking about?

And is the president’s memory all that he cracks it up to be?