Russia's Ambassador to the United States Alexander Darchiev, 66, died suddenly Wednesday, the Russian Foreign Ministry announced.

"The leadership and staff of the Russian Foreign Ministry report with deep sorrow that on Nov. 11, at the age of 66, the Ambassador Extraordinary and Plenipotentiary of the Russian Federation to the United States of America, Alexander Nikitich Darchiev, passed away suddenly," Vladimir Putin appointed Darchiev, a veteran diplomat known in the past for his public denunciations of the West, as ambassador to Washington in March 2025 to lead a rapprochement with the Trump administration that has rattled Ukraine, the European Union and NATO.

His death comes less than a week after a White House news conference hailing a temporary ceasefire in Ukrainian territory occupied by Russia.

Shortly after being tapped as ambassador, Darchiev met with Trump administration officials and delivered a message of hope for peace.

"Russia and the United States are destined, as great powers, to have non-confrontational peaceful existence," Darchiev said during a June 10, 2025, Russia Day reception at the Russian Embassy in Washington after delivering his credentials to the White House, adding, "our discussion was very constructive."

Before taking the helm of the Russian Embassy in Washington, Darchiev played a role as the Kremlin’s point man for high-stakes bilateral negotiations, most notably during the delicate discussions that led to prisoner swaps involving imprisoned arms dealer Viktor Bout and detained Americans Brittney Griner and Paul Whelan.

In August 2022, while serving as the director of the Russian Foreign Ministry’s North American Department, Darchiev provided the first on-the-record Russian confirmation that Moscow and Washington were actively discussing those situations.

"This quite sensitive issue of the swap of convicted Russian and U.S. citizens is being pursued along the channels designated by our presidents," Darchiev told the Russian state news agency TASS. "The individuals are, indeed, being discussed. The Russian side has long been seeking the release of Viktor Bout. The negotiations are bearing fruit."

His comments marked a breakthrough moment in months of backchannel diplomacy, which ultimately culminated in December 2022 when the U.S. and Russia completed a one-for-one swap of Griner for Bout at an airport in Abu Dhabi.

Fox News' Gillian Turner, The Associated Press and Reuters contributed to this report.