Hegseth was returning to the United States from a NATO defense ministers meeting in Brussels when his plane made the unscheduled landing at an unnamed airport in Britain, a spokesperson said.

"The plane landed based on standard procedures and everyone onboard, including Secretary Hegseth, is safe," Pentagon spokesman Sean Parnell said on social media.

"All good. Thank God. Continue mission!" Hegseth posted in reply.

At the NATO meeting, Hegseth called for member countries to contribute more military aid to Ukraine in its fight against Russia's invasion.