Jill Biden met with US service personnel at Mihail Kogalniceanu air base in Romania on Friday, the first stop on a four-day visit to Eastern Europe.

The US first lady served food and cakes to US troops at the base, and delivered a few bottles of ketchup that drew applause.

She is using her second solo trip abroad to focus on the Ukrainian refugee crisis by visiting Romania and Slovakia, where she will spend Mother's Day meeting displaced families in a small Slovak village on the border with Ukraine.

Biden will also use her four days in Europe to highlight issues she champions at home, such as support for the US military, education and child welfare.