US warns China on militarization of East Sea

"China must not pursue militarization in the East Sea," Carter said in a wide-ranging speech at the Commonwealth Club in San Francisco. "Specific actions will have specific consequences."

Asked what the consequences could be, Carter told reporters the US military was already increasing deployments to the Asia-Pacific region and would spend US$425 million through 2020 to pay for more exercises and training with countries in the region that were unnerved by China's actions.

He said China's behavior had fueled trilateral agreements that would have been "unthinkable" even a few years ago.

The United States has carried out several freedom of navigation exercises in the East Sea recent months, sailing near disputed islands to underscore its rights to navigate the seas. US Navy officials say they plan to conduct more and increasingly complex exercises in the future.

Carter said the Pentagon also planned to spend over US$8 billion in fiscal 2017 alone to expand its fleet of powerful submarines and undersea drones.

"There is no question that there are consequences for these actions," Carter said. "We have plans in all three of these categories. You'll see them unfolding."

Carter underscored the US military's determination to safeguard maritime security around the world, and particularly in the East Sea region, which sees about 30% of the world's trade transit its waters each year.