Kurt Campbell attends a China Development Forum in Beijing, China March 23, 2019. (Photo: REUTERS)

Campbell said the United States needed more diplomatic facilities across the region, and more contact with Pacific island countries that at times "receive lesser attention."

"You will see more cabinet-level, more senior officials, going to the Pacific ... recognizing that nothing replaces, really, diplomatic boots on the ground," he told Washington's Center for Strategic and International Studies.

The Biden administration has vowed to commit more resources to the Indo-Pacific as China seeks to boost economic, military and police links with Pacific island nations hungry for foreign investment.