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."

"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.