“I wanted to come on Mother’s Day,” Biden said before the start of a closed-door meeting between the two first ladies. “I thought it was important to show the Ukrainian people that this war has to stop and this war has been brutal and that the people of the United States stand with the people of Ukraine.”

Zelenska praised Biden “for a very courageous act” in coming to Ukraine.

“We understand what it takes for the U.S. first lady to come here during a war when the military actions are taking place every day, where the air sirens are happening every day, even today,” she said in Ukrainian through an interpreter.

The unannounced Biden visit came amid a four-day swing through Eastern Europe for the first lady — her highest-profile diplomatic engagement since President Biden took office. She entered Ukraine the day before Russia’s Victory Day, which some officials worry will bring a new, more violent, phase of the war.

Previous first ladies have made overseas visits to support U.S. troops stationed abroad, but few have visited an active war zone on their own. In 2005, Laura Bush traveled solo to Kabul, where she met with women who were training to be teachers and gave presents to Afghan children on the street. Bush returned to Afghanistan in 2008.

Jill Biden’s trip to this region comes at a high-stakes moment in American foreign policy, as the United States plays a leading role in the military conflict and global humanitarian response. The invasion marks the moment of highest U.S.-Russia tension since the end of the Cold War.

Biden and Zelenska have exchanged correspondence in the last few weeks, a U.S. official said.

At a school here in Uzhhorod, the two women entered a classroom and sat down at a table with children working on art projects for their mothers. The children were crafting cardboard and tissue paper bears, which represent the symbol of the Zakarpattia oblast.

Biden’s trip to Ukraine follows two high-profile visits from American leaders in recent weeks. House Speaker Nancy Pelosi (D-Calif.) led a congressional delegation to Kyiv to meet with Ukrainian President Volodymyr Zelensky late last month, following a trip by Secretary of State Antony Blinken and Secretary of Defense Lloyd Austin.

President Biden has not traveled to Ukraine since the war began, with aides privately citing the security challenges that a visit would pose. In March, he visited Rzeszow, Poland, which is about 60 miles from the Ukrainian border.

Biden and other Group of Seven leaders were scheduled to hold a video call with Zelensky later on Sunday. A White House official said the leaders planned to discuss Russia’s ongoing invasion and how the G-7 countries could continue to support Ukraine and levy costs on Moscow.

Before crossing the border, Jill Biden visited a bus station in Kosice, Slovakia, where local officials and nongovernmental organizations have set up a refugee processing center. Biden heard emotional stories from refugees who fled Ukraine but expressed a strong desire to return to their home country.

Victoria Kutocha, a mother of three whose husband remained in Ukraine to fight in the military, told Biden of her journey to Slovakia and her outrage at Russia’s explanation for its invasion.

“They come to our land,” she told Biden. “They kill us, but they say we protect you.”

Hugging her 7-year-old daughter, Yulie, Kutocha described the difficulty of explaining to her children why they had to leave their home. “It’s impossible,” she said. “I try to keep them safe. It’s my mission.”

“It’s senseless,” Biden said.

Biden began her trip in Romania, where she met troops at the Mihail Kogalniceanu Air Base and visited a school in Bucharest hosting Ukrainian children. Biden will return to Bratislava, Slovakia, on Sunday night, and on Monday she is slated to meet with Slovakian President Zuzana Caputova.