He did that in spite of the fact that he had been warned not to do so by his national security advisers -- including in briefing papers emblazoned with the words "DO NOT CONGRATULATE," according to The Washington Post

Because of course he did.

The reasons why not to offer congratulations to Putin are many.

First and foremost, Putin's victory -- in which he won more than 70% of the vote -- wasn't a democratic election of any sort. Putin controls not only the levers of government but also the state-run media.

"An American president does not lead the free world by congratulating dictators on winning sham elections," Sen. John McCain, an Arizona Republican, said in a statement.

Then there is the poisoning of an ex-Russian spy and his daughter with a nerve agent while on British soil earlier this month, an act that British Prime Minister Theresa May has laid at the feet of the Russians. (Trump and his administration have been less willing to point the finger directly at Russia.)

And, finally, let's not forget that Russia actively sought to interfere in the 2016 presidential election, a move widely expected to be replicated in future US elections. Despite that unanimous conclusion by the US intelligence community, Trump has been wary of putting the full blame for election meddling on the Russians. Trump did, however, install sanctions against Russia for its election interference -- albeit it was well after many in Congress had hoped he would do so.

So why, given all of those red flags -- not to mention the whole "DO NOT CONGRATULATE" thing -- would Trump offer up his kudos to Putin on a re-election "victory"?

The Post notes that it's not clear Trump actually read the briefing papers.

But the same reason "DO NOT CONGRATULATE" was written on the briefing documents is exactly why Trump decided to congratulate Putin. Because all of the nerds and eggheads who try to manage his every utterance said not to do it.

One of the lessons of Trump's first year in office is that the best way to get him to do something is to tell him he absolutely, under no circumstances, 100% cannot do it. That doing it would be a massive breach of protocol. That no president who sat in the Oval Office before him had ever done something like it.

Putting "DO NOT CONGRATULATE" on a briefing document for Trump is like waving a red cape in front of a bull.

Remember that the defining lens through which Trump views the world is as an outsider looking into a club that the supposed smart and classy people won't let him into. He has disdain to spare for elites and establishment figures who try to lecture him on how to act or what to say.

The 2016 election, in Trump's mind, validated that long-held suspicion of the people who claim to know best. They all said he had no chance. They laughed at him. And he beat them all -- his way.

Since taking over the presidency, Trump has repeatedly bridled at those who try to manage him or make him fit into a more conventional box.

While the White House publicly insists that Trump's relationship with national security adviser H.R. McMaster is hunky dory, reporting coming out of 1600 Pennsylvania Avenue suggests that Trump fumes about the gruff and what he perceives to be arrogant way McMaster deals with him. Rumors of McMaster's departure -- and who might replace him -- have been swirling for months.

Which brings us back to Trump's call with Putin. Combine Trump's natural resistance to do what other people tell him to do with his distrust of McMaster and his desire to break new ground in the US relationship with Russia and it's a near guarantee that Trump was going to do exactly what he wanted to when it came to congratulating Putin -- "DO NOT CONGRATULATE" be damned.