U.S. Defense Secretary James Mattis plans to travel to Japan and South Korea next month – his first trip as the head of the Pentagon, a spokesman said Wednesday.

“The trip will underscore the commitment of the United States to our enduring alliances with Japan and the Republic of Korea, and further strengthen U.S.-Japan-Republic of Korea security cooperation,” Pentagon spokesman Jeff Davis said.

Mattis will depart February 1 for South Korea and travel on to Tokyo two days later. During his confirmation and his first days at the Pentagon, Mattis stressed the importance of maintaining international alliances.

U.S. President Donald Trump, however, had threatened during the campaign to withdraw American forces from South Korea and Japan if they did not pay more for the military support.

The first of Trump’s cabinet picks to be confirmed, Mattis served as the commander of U.S. Central Command and was NATO’s commander for transformation while in uniform; he retired from military service in 2013.