Tensions have risen in the South China Sea over recent incidents between Chinese and Vietnamese and Philippine ships, the latest confrontations in a potential global flashpoint where the United States challenges China's sweeping maritime claims.

He also said he regretted that he was unable to meet with North Korean representatives at the forum, adding that Washington is "ready to go" with restarting denuclearisation talks with Pyongyang after it test-launched a missile the previous day.

Pompeo said he had urged regional allies "to maintain the sanctions that spur diplomacy with North Korea, to speak out against Chinese coercion in the South China Sea, to advocate for the voluntary safe and dignified return of the Rohingya to their homeland, and to confront Iranian aggression."