Russia’s Ambassador to the United States, Alexander Darchiev, has died at the age of 66, the Russian Foreign Ministry said Wednesday. “An outstanding diplomat, experienced leader, kind colleague and mentor has passed away,” the ministry said in a brief statement, describing the late ambassador as a “professional of the highest order and a brilliant expert on American affairs.” It did not disclose the cause of Darchiev’s death. Darchiev replaced Anatoly Antonov as ambassador to the United States in early 2025 amid a sudden thaw in U.S.-Russia relations following President Donald Trump’s return to the White House.