The leaders of the U.S., Japan and South Korea presented a united front on Friday when they met at the U.S. presidential retreat of Camp David in Maryland.

"Ours is a partnership built not just for our people but for the entire Indo-Pacific," they said in a joint statement.

Cooperation will go beyond the security to encompass supply chains, economy and technology in response to the threats posed by China, Russia and North Korea.

They singled out China in particular. "We share concerns about actions inconsistent with the rules-based international order, which undermine regional peace and prosperity," they said, and "strongly oppose any unilateral attempts to change the status quo in the waters of the Indo-Pacific."

They also reaffirmed the importance of peace and stability in the Taiwan Strait and urged a peaceful resolution of cross-Strait issues. Just three hours after the trilateral summit ended, China conducted military drills there in a show of defiance.