Donald Trump’s love affair with Vladimir Putin may end in the White House. The realities of Great Power Politics make it almost inevitable.

On the face of it, all it would take is a few strokes of the pen, once Trump is sworn in as president, to usher in a new era of respectful cooperation with the former Cold War protagonist. The acts passed by Congress sanctioning Putin’s inner circle, their business interests, and key state-controlled companies can be waived on the grounds of national security, if the new president desires.

“The only requirement is that he send a letter to Congress explaining why, and that could be a very short letter,” says Rory MacFarquhar, a visiting fellow at the Peterson Institute for International Economics in Washington, D.C., who was formerly chief economist for Russia with Goldman Sachs, before joining the Obama administration as an adviser on economic policy.

That would send the clearest possible signal of a desire to “reset relations,” and would drastically relieve the pressure that Russia’s economy has been under for the last two and a half years. Russia’s gross domestic product is set to shrink for its second year in a row this year, by 1.8%, according to International Monetary Fund projections.

But Trump can’t waive the sanctions without spending significant political capital. There are few friends of Russia in Congress, and fewer still in the State Department. And he can’t signal anything to Putin without signaling it to the rest of the world. Annexations? Fine. Fomenting civil war in neighboring countries? No problem by us, the leaders of the free world.

But even if Trump does just that, Putin’s own political situation will make it hard for him to make Russia a less troublesome and disruptive partner on the world stage, analysts say.

“It is hard to overstate how far from the Washington foreign policy consensus such a move would be,” MacFarquhar says. “All of the criticism of Obama was that he was doing too little, so it would be really something for Trump to say now that ‘too little’ was too much.”

Russians appreciate that, too, and they don’t appear to be placing too much faith in Trump’s ability to change U.S. policy into something more amenable to themselves.

“He is ready to establish dialogue with Russia,” said Dmitry Trenin, an analyst at the Carnegie Institute for International Peace in Moscow. “However, if you take the Republican camp in general, there won’t be agreement and unanimity [on how to deal with Russia].”

Trenin’s view reflects the reality that U.S. policy of stopping Russia from reasserting its power in the former Soviet Union–whether in Georgia, the Baltics or Ukraine–changed more in style than in substance after Hillary Clinton’s ill-fated “reset.”

Mark Galeotti, director of the consultancy firm Mayak Intelligence and a visiting professor at the Moscow State Institute for International Relations, argued in his blog last week that the Kremlin might not even like or want Trump as president. “The Russians never expected Trump to win, and their calculus [in disrupting the election] was based on trying to ensure a Clinton presidency was weakened from the gate,” he said.

Although the Kremlin-backed media demonized Clinton as a warmonger by ahead of the election, she at least had the attraction of being a known quantity. “The Kremlin might actually feel it has to be a little more cautious and predictable, precisely because it is dealing with someone who actually internalizes the kind of devil-may-care belligerence Putin affects,” Galeotti argued.

The biggest problem for Trump could be that he can’t reasonably expect much from Putin in return. Putin has spent the last decade orchestrating an increasingly strident anti-Americanism at home, to rally his people around the flag while their incomes and civil liberties eroded.

“If the Kremlin cannot secure big strategic concessions for its domestic audience, then it will need to keep vilifying the West to sustain nationalist support,” Stratfor analysts said in a research note Friday.

Putin himself is facing re-election in 2018, and while he enjoyed whole-hearted support for raising living standards in his first decade, big cuts to health and education spending in order to ringfence a bloated military budget will create an awkward backdrop in 18 months’ time.

As the exiled journalist Oleg Kashin wrote in Monday’s Guardian: “Now, Putin’s main foreign policy objective must be to fall out with Trump, because without that, the Kremlin will have no one to blame for Russia’s problems but Russia.”

And that would be a problem indeed.