A State Department official announced that the senior U.S. diplomat to Europe, Karen Donfried, will step down to focus on her family.

The largest European war since World War Two and the U.S. attempt to unite the West against Russia have shaped Assistant Secretary Donfried’s 18-month tenure.

She traveled to Europe with U.S. Secretary of State Antony Blinken to heal and re-energize transatlantic ties harmed by former president Donald Trump’s unilateral attitude.

When Russian planes intercepted a U.S. drone over the Black Sea, she met with Russia’s senior envoy in Washington last Tuesday.

The first open clash between Washington and Russia since the invasion of Ukraine has strained relations between the two former Cold War enemies.

The Department spokesman stated she would leave at the end of March. Her replacement to lead the Bureau of Europe and Eurasian Affairs, which includes 50 nations from the U.K. to Azerbaijan, is unknown.

“Karen has effectively handled our ties with many of our most important friends and partners at a time when Moscow aggression endangered decades of peace and prosperity,” Blinken told Reuters before publication.

“Her policy acumen, ethics, and determination distinguished her leadership as Assistant Secretary and exemplify the greatest qualities of public service,” Blinken said.

The soft-spoken foreign policy expert-turned-diplomat was one of the last top U.S. officials to visit Moscow before Russia invaded Ukraine on Feb. 24, 2022. She joined Blinken in Kyiv in September following the conflict.

She addressed U.S. worries about Russia’s military buildup near Ukraine during her December 2021 visit to Moscow.

Since the conflict began, intelligence chiefs and diplomats have occasionally spoken with Russia in foreign countries and at international conferences.

Russia disputed the drone incident on Tuesday and ordered America to stay out of its airspace.

Moscow said the drone’s flight proved the U.S. was actively involved in the Ukrainian war, which the West has avoided.

Donfried was senior director for Europe at the National Security Council in the Obama administration and a member of the State Department’s policy planning team in the Bush administration, where he developed a big-picture strategy.

Before entering the Biden administration, she was the first female German Marshall Fund president.