New U.S. Indo-Pacific Command chief Adm. John Aquilino pledged Friday to maintain a "free and open" region and provide the deterrence needed to prevent "great power conflict" amid China's growing assertiveness.

Calling the rules-based international order the foundation for the region to thrive and prosper, Aquilino said during a change of command ceremony in Hawaii to replace Adm. Philip Davidson that the environment the United States and its allies have created for decades is "being challenged."

New U.S. Indo-Pacific Command chief Adm. John Aquilino. (Photo courtesy of U.S. Navy)(Kyodo)

"We are committed to strengthening the relationships with our allies and partners across the globe. We are committed to providing the deterrence needed to prevent great power conflict, and should it be directed, we're committed to be able to fight tonight and win," he said.

Davidson, in his speech, directly mentioned China and warned of its ambitions to expand its influence in the region and its authoritarianism.

"Make no mistake, the Communist Party of China seeks to supplant the idea of a free and open international order with a new order -- one with Chinese characteristics, one where Chinese national power is more important than international law," he said.

"But the strategic competition in the Indo-Pacific is not between our two nations. It is a competition between liberty, the fundamental idea behind a free and open Indo-Pacific, and authoritarianism -- the absence of liberty and the objective of the Communist Party of China," he added.

The remarks echoed U.S. President Joe Biden's framing of the competition between the United States and China as a clash between democracies and autocracies. The administration has been rallying allies and like-mind countries to counter China's rise.

In Hawaii on Thursday, the top uniformed officers of the United States, Japan and South Korea shared their concerns about North Korea's nuclear and missile programs, according to the U.S. Joint Chiefs of Staff.

U.S. Chairman of the Joint Chiefs of Staff Gen. Mark Milley and his Japanese and South Korean counterparts -- Koji Yamazaki and Won In Choul -- also discussed the importance of promoting a rules-based international order in the region, it said.

It was the first in-person meeting between the most senior U.S., Japanese and South Korean military officers since the onset of the coronavirus pandemic, according to a press release issued Friday by the Joint Chiefs of Staff.

The last trilateral discussions between the top uniformed officers took place virtually in November.