WASHINGTON/TAIPEI (Reuters) - U.S. Secretary of State John Kerry said on Wednesday the United States expects to have “very serious” talks with China about militarization of the South China Sea after reports that Beijing deployed advanced surface-to-air missiles to a disputed island.

Taiwan’s Defense Ministry said the missile batteries had been set up on Woody Island in the Paracels chain, which has been under Chinese control for decades but also is claimed by Taiwan and Vietnam.

A U.S. defence official also confirmed the “apparent deployment” of the missiles, first reported by Fox News.

“There is every evidence, every day that there has been an increase of militarization of one kind or another,” Kerry told reporters when asked about the reported deployment. “It’s of serious concern.

“We have had these conversations with the Chinese and I am confident that over the next days we will have further very serious conversation on this.”

The United States claims no territory in the South China Sea but has expressed serious concerns about how China’s increasingly assertive pursuit of territorial claims there could affect the vital global trade routes that pass though it.

Chinese Foreign Minister Wang Yi told reporters the “limited and necessary self-defence facilities” China had on islands and reefs where it has personnel stationed was “consistent with the right to self-protection that China is entitled to under international law.”

The Chinese Defense Ministry told Reuters the latest reports about missile deployment were nothing but “hype.”

China claims most of the South China Sea, through which more than $5 trillion in global trade passes every year. Vietnam, Malaysia, Brunei, the Philippines and Taiwan have rival claims.

Chinese Foreign Minister Wang Yi speaks at a joint news conference with Australian Foreign Minister Julie Bishop at the Ministry of Foreign Affairs in Beijing, China, February 17, 2016. REUTERS/Kim Kyung-Hoon

TOPIC AT ASEAN MEETING

News of the missile deployment came as U.S. President Barack Obama and leaders of the Association of Southeast Asian Nations concluded a summit in California, where they discussed the need to ease tensions in the South China Sea.

It also followed a patrol by a U.S. Navy destroyer within 12 nautical miles of Triton Island in the Paracels last month, a move China condemned as provocative.

The United States also has conducted sea and air patrols near artificial islands that China has built in the Spratly islands chain farther south in the South China Sea, including by two B-52 strategic bombers in November.

Obama said the United States planned to continue such patrols in the name of freedom of navigation.

Admiral Harry Harris, commander of the U.S. Pacific Command, said at a news briefing in Tokyo that deployment of missiles to the Paracels would not be a surprise but would be a concern and contrary to China’s pledge not to militarize the region.

Some analysts believe China’s increasing military presence in the South China Sea could lead to a Beijing-controlled air defence zone there.

“(The missile deployment) reinforces the view that China intends to exert growing control in these international waters, including potentially by declaring an Air Defense Identification Zone,” said Rory Medcalf, head of the National Security College at the Australian National University.

Mira Rapp-Hooper, a South China Sea expert from the Center for a New American Security, said it was not the first time China had sent air-defense missiles to the Paracels, but the latest move appeared to be a response to U.S. patrols.

She noted that while China had said it did not seek to militarize islands and reefs in the Spratly Islands, it had made no such commitment for the Paracels, where it has stationed military assets for years.

Ni Lexiong, a naval expert at the Shanghai University of Political Science and Law, said Woody Island belonged to China.

“Deploying surface-to-air missiles on our territory is completely within the scope of our sovereign rights,” he said. “We have sovereignty there, so we can choose whether to militarize it.”

Fox News said images from civilian satellite firm ImageSat International show two batteries of eight surface-to-air missile launchers on Woody Island, as well as a radar system.

The missiles arrived in the past week and, according to a U.S. official, appeared to show the HQ-9 air defence system, which has a range of 125 miles (200 km) and would pose a threat to any airplanes flying close by, the report said.