The U.S. ambassador to the United Nations made a rare visit to Tokyo on Thursday, following a four-day trip to South Korea, as part of a push to bolster the U.N.’s relevance together with its two allies — which both currently sit on the Security Council — and counter nuclear-armed North Korea.

The U.S. will also continue to support the expansion of the U.N. Security Council, as well as the granting of a permanent seat to countries including Japan, Linda Thomas-Greenfield, the U.S. envoy to the U.N., said during an event at the National Graduate Institute for Policy Studies on Thursday.

“The Security Council of 70 years ago does not reflect the realities of today,” Thomas-Greenfield said, noting that the U.S. shifted its stance toward supporting Security Council reform in 2021.