Outgoing U.S. Secretary of State John Kerry said on Friday he was confident the next administration would stick to the same peaceful principles on Asian security as the current one, despite hawkish comments from President-elect Donald Trump's cabinet picks.

Referring to the disputed East Vietnam Sea, Kerry told a university audience in Ho Chi Minh City that countries, big or small, should refrain from provocation and any dispute should be resolved peacefully in accordance with international law.

Kerry said he was "confident the next administration will continue to adhere to the same good faith with the policies that I just articulated."

His comments came after his nominated replacement, Rex Tillerson, said the United States must send a clear signal to China that its island-building in the East Vietnam Sea must stop and that its access to those islands must not be allowed.

On Thursday, Trump's pick to lead the Pentagon, retired Marine General James Mattis, said Russia, China and Islamist militants were presenting the biggest challenge to the U.S.-led world order since World War Two, and called for Congress to lift spending caps undermining military readiness.

China claims most of the energy-rich East Vietnam Sea, through which about $5 trillion in ship-borne trade passes every year. Neighbours Brunei, Malaysia, the Philippines, Taiwan and Vietnam also have claims.

China has reclaimed seven reefs in the area, building man-made islands with anti-aircraft and anti-missile batteries, satellite images show.

The Philippines, which is seeking to improve ties with Beijing, said any U.S. action to drive China from the artificial islands would be its own prerogative, and in its own national interest.

Foreign Secretary Perfecto Yasay was replying to a question during a television interview about Tillerson's comments.

"They said that they would prevent China from doing or undertaking these kind of activity. If it wants to do that, they have the force to do so, let them do it," Yasay said.

China has built several artificial islands in the exclusive economic zone of the Philippines, which an arbitration tribunal in The Hague last year ruled unlawful.

Philippine President Rodrigo Duterte reiterated last month he wanted to avoid confrontation with China and saw no need to press Beijing to abide by the ruling.

Yasay earlier said the Philippines wanted to strengthen ties with the United States and that Washington should be an "influential force" in Asia and help maintain balance there.

He said he hoped the new government in Washington would refrain from criticising countries, as the Obama administration had over the Philippines’ deadly drugs war, and he welcomed Tillerson's views that decisions and comments should be based on facts.