An uptick in Chinese maritime exercises in the Pacific is a "natural evolution" and the drills will grow in complexity as the navy boosts its capacity, commander of the U.S. 7th Fleet Vice Adm. Robert Thomas said.

China is expected to keep up a "steady drumbeat" of exercises in the region, Thomas told reporters Tuesday at the opening ceremony of a bilateral naval exercise with Singapore known as CARAT Singapore.

"This is a natural evolution for the PLAN as they improve their professionalism, as they improve both their capacity and capability," he said, referring to the People's Liberation Army Navy. "You should expect more exercises, and frankly more complex exercises."