Trump thought he had a nuclear deal with Putin. Not so fast, Russia said.

Trump thought he had a nuclear deal with Putin. Not so fast, Russia said.

U.S. President Donald Trump had a pre-election plan to show he had gotten something out of his mysteriously friendly relationship with President Vladimir Putin of Russia.

In the weeks before the election, the two men would announce that they had reached an agreement in principle to extend New START, the last remaining major arms control agreement between the two countries. It expires Feb. 5, two weeks after the next U.S. presidential inauguration.

Trump has long refused to sign off on a clean five-year extension of the agreement, a step that both leaders could take on their own accord. He has described the Barack Obama-era treaty as deeply flawed — the same thing he said about the North American Free Trade Agreement and the Iran nuclear accord — because it did not cover all of Russia’s nuclear arms or any of China’s.

But if Putin is really rooting for Trump to be re-elected, he is not acting like it.

On Tuesday, Marshall Billingslea, Trump’s lead negotiator, announced that the two leaders had an “agreement in principle, at the highest levels of our two governments, to extend the treaty.” Billingslea described an added “gentleman’s agreement” to cap each country’s stockpile of weapons not currently deployed on missiles, submarines or bombers. Details needed to be worked out, he cautioned, including the tricky work of verifying compliance.

It sounded like a promising solution, for a few hours.

Then the Russian deputy foreign minister, Sergei A. Ryabkov, shot back that this was a figment of someone’s election-season imagination.