What’s the appropriate, slightly unhip portmanteau to describe the relationship between Donald Trump and Vladimir Putin these days? Is it a bromance? Are are the two men frenemies?

The hot-and-cold humors of adolescence, as well as its fluid network of grudges and shifting alliances, have been on display this week between the U.S. president-elect and the Russian president, culminating in a bizarre Friday evening Twitter missive from Trump:

Here we have the president-elect quoting an oppressive foreign leader’s snark in the service of spiking the football on an opponent Trump vanquished nearly two months ago— with the Trumpian flourish of “So true!” perfectly tying it all together.

The tweet capped off a Putin swoon that also included Trump’s release Friday of an apparent letter from the Russian.

“Please accept my warmest Christmas and New Year greetings,” Putin wrote, according to an “unofficial translation” released by the Trump team. Trump did not release the original letter. “I hope that after you assume the position of the President of the United States of America we will be able—by acting in a constructive and pragmatic manner—to take real steps to restore the framework of bilateral cooperation in different areas as well as bring our level of collaboration on the international scene to a qualitatively new level.”

But this type of friendship is fickle and flickering. Trump might release a fawning letter from Putin, and he might be perfectly happy to quote Putin dissing Hillary Clinton—the enemy of my enemy is at the very least my frenemy, and possibly my friend, after all—but that doesn’t mean they won’t have their differences.

On Thursday, Putin said in a speech that he intended to strengthen Russian nuclear-weapons capabilities. Trump responded, as he does, on Twitter, writing, “The United States must greatly strengthen and expand its nuclear capability until such time as the world comes to its senses regarding nukes.” That set off a mad spin effort, as Trump spokesman Jason Miller insisted that what the president-elect really meant, contra a plain reading of the words he used, was to warn about “the threat of nuclear proliferation and the critical need to prevent it—particularly to and among terrorist organizations and unstable and rogue regimes.”

Lest anyone be tempted to believe this up-is-down spin, Trump made sure they didn’t, telling MSNBC’s Mika Brzezinski, “Let it be an arms race. We will outmatch them at every pass and outlast them all.”

Trump seems to be making policy on the fly again. Is it just a machismo contest with his pal Putin? Is he intentionally spiting President Obama, who has tried to effect nuclear-weapons reductions? (Is Trump paying close enough attention to know about Obama’s efforts?) Is he just trying to keep everyone, including apparently his aides, guessing?

Putin made his comments about losing with dignity in a year-end press conference, in which he had plenty of punditry to offer on U.S. politics. Although the consensus that Russian hackers were behind attacks on the Democratic National Committee and Democratic politicians during the campaign, and although many U.S. intelligence agencies have come to the conclusion that those hacks were intended to hurt Clinton and aid Trump, Trump and Putin have both insisted Russia was not the culprit.

“The president-elect was absolutely right to note that nobody knows who these hackers are,” said Putin, a cynical sneer underpinning his Cheshire Cat grin. “Maybe they were in a different country, and not in Russia. Maybe it was just someone sitting on their sofa or bed. It’s very easy now to show one origin country, when you’re actually in a different place.” Putin criticized the Democratic Party for “trying to chalk their own failures up to outside factors,” which he said “is not very dignified.” As for Trump, Putin said, “Nobody believed he’d win. Except us, of course. We always believed.” Of course, if the intelligence assessments are correct, Putin knows very well where the hacks came from, and while there are many culprits in Clinton’s loss, the leaked information does appear to have been one more thumb on the scale weighing against her.

Russia’s ever-bolder online espionage, and its expansionist saber-rattling in Eastern Europe and the Caucasus, have led some to wonder whether the world is witnessing a return to the Cold War. (Back in those days, Putin was a KGB official and Trump was, among other things, a prospective Moscow investor.)

But the on-again, off-again flirtation between Trump and Putin raises the scary prospect that the world might face many of the worst, most dangerous tendencies of the Cold War, without any of the best. On the bad side of the ledger, Trump is offering to return the world to apocalyptic nuclear arms races and seeking to borrow the old Soviet technique of building massive walls. Yet given Trump’s tendency to accommodate Putin’s oppression and territory-grabbing impulses, as well as his own authoritarian leanings, the president-elect seems unlikely to be a muscular, outspoken defender of democracy around the globe or of dissidents within Russia. Trump’s bizarre tweet might be entertaining if it didn’t seem like a harbinger of a world that is more violent and less free. So true!