Sergey Kislyak, Washington’s most famous – or infamous -ambassador, is heading back to Russia

Remarkably fresh despite the tropical heat, Russian Ambassador Sergey Kislyak was doing what he does best: hobnobbing in a room full of diplomats and dignitaries.

Only the setting was unusual for the most famous – or infamous – foreign envoy assigned to Washington in decades. He was in Cancun, Mexico, last week on the sidelines of a meeting of the Organisation of American States, a regional body.

What in the world was Kislyak doing there?

“I am representing Russia,” Kislyak said.

But he will not be doing that much longer, at least not in the United States.

The veteran Russian diplomat at the centre of much of the FBI investigation into Moscow’s meddling in the US presidential election and its aftermath is stepping down after nearly a decade as ambassador.