White House national security adviser John Bolton’s unexpected meeting with “the last dictator in Europe” could undermine a vital Russian alliance, with potentially high stakes for Russian President Vladimir Putin himself.

“It is extraordinary that Ambassador Bolton went to Belarus,” Heather Conley, director of the Europe Project at the Center for Strategic and International Studies, told the Washington Examiner. “It’s clearly a strong message to the Kremlin, that — as the Kremlin becomes more deeply involved in our neighborhood, whether that’s Cuba or Venezuela — the U.S. will play a more assertive role in its neighboring countries.”