A year after defeating Hillary Clinton in the 2016 presidential election, President Donald Trump is still really, really angry that the federal government he runs isn’t going after her.

Everybody is asking why the Justice Department (and FBI) isn't looking into all of the dishonesty going on with Crooked Hillary & the Dems.. — Donald J. Trump (@realDonaldTrump) November 3, 2017

....People are angry. At some point the Justice Department, and the FBI, must do what is right and proper. The American public deserves it! — Donald J. Trump (@realDonaldTrump) November 3, 2017

But while the president has been known to use tweets to set federal policy (as he did while announcing a ban on trans service members in the US military, without warning the Pentagon he would be doing so), Friday morning’s tweets don’t actually mean he’s ordering the federal government to prosecute his electoral opponent based on the president’s own conviction that she committed a crime.

They actually mean that Trump may have finally accepted, apparently belatedly, that he can’t actually order the federal government to go after his political opponents — and he’s really, really not happy about it.

Trump opened up to talk-radio host and Mediaite contributor Larry O’Connor on Thursday, in an interview broadcast on Washington radio station WBAL. “The saddest thing,” Trump told O’Connor, “is because I’m the president of the United States, I’m not supposed to be involved in the Justice Department.”

This is quite the quote from Trump, saying he hopes the DOJ will be 'doing something' about Clinton. https://t.co/cUbcujm3pi pic.twitter.com/KtaiKWojQ8 — Kyle Griffin (@kylegriffin1) November 3, 2017

The idea that the head of the government can’t use his power to prosecute his enemies is literally at the core of the idea of the “rule of law” as it’s understood in America. Outside legal experts and lawmakers from both parties have been making that argument for months.

But it seems that it came as a nasty surprise to President Donald Trump, and it’s not clear when he found out that he couldn’t manipulate the activity of the Justice Department — of if he has, in fact, made a decision he won’t try to soon reverse.

Remember that he certainly didn’t seem to know that he wasn’t “supposed to be involved” when he (allegedly) demanded the loyalty of FBI Director James Comey; fired Comey (ostensibly for being too harsh on Hillary Clinton), and later admitted that he’d fired Comey because he thought the FBI’s investigation of ties between his campaign and the Russian government was “fake news.”

And he certainly didn’t know he wasn’t “supposed to be involved” when for months he held a grudge against his own attorney general and close adviser Jeff Sessions, because Sessions felt that his entanglement in the Russia scandal was a reason to recuse himself from the federal investigation rather than trying to quash it. (That move led to the eventual appointment of special counsel Robert Mueller, who indicted former Trump campaign manager Paul Manafort earlier this week.)

It is not ideal, to say the least, for a president to learn on the job about fundamental principles of American governance. But it appears that at some point, someone got through to him, and explained that Comey and Sessions weren’t acting deliberately to spite the president but were trying to uphold the integrity of their offices. So on one level, Trump’s petulant tweets about the need for the FBI and DOJ to listen to public outcry and start going after “Crooked Hillary” are just that: petulant.

But there’s also the more sinister possibility that Trump is trying to use his public platform to make the FBI, and the ongoing Mueller investigator, to feel public and congressional pressure to reopen their case against Clinton. Put another way, he’s deliberately using his Twitter account as a literal bully pulpit.

That is also not how the federal government is supposed to work. The DOJ doesn’t poll the public about which cases it should open. But it’s not clear that Donald Trump knows just how deep prosecutorial independence is supposed to go — or if he cares.