WASHINGTON: The clash between China and the U.S. over who will control the South China Sea , one of the world’s busiest waterways, escalated Wednesday as Secretary of State John F. Kerry lashed out at Beijing after the Obama administration said it confirmed reports that China had deployed advanced surface-to-air missiles on a built-up island it occupies in the contested sea.

China struck back forcefully a day after President Obama met with a group of Southeast Asian leaders, accusing Washington and its allies in the region of making exaggerated claims in a bid to isolate China.

Kerry said administration officials intend to have a “very serious conversation” over the matter with their counterparts in Beijing and suggested that Chinese President Xi Jingping reneged on a promise he made during a visit to the White House in September.

“When President Xi was here in Washington, he stood in the Rose Garden with President Obama and said China will not militarize the South China Sea ,” the secretary of state told reporters. “But there is every evidence, every day that there has been an increase of militarization of one kind or another.”

Kerry made the comments after Taiwanese officials said the Chinese navy had set up surface-to-air missile batteries on Woody Island, a tiny patch within the South China Sea’s Paracels chain that has been under effective Chinese control for decades but is also claimed by Taiwan and Vietnam.

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

Beijing denied the reports, asserting that defense facilities on “relevant islands and reefs” had been in place for many years. The Chinese Defense Ministry also said in a statement that Western media reports of a missile deployment were “hype” aimed at stoking regional fears toward China.

Chinese Foreign Minister Wang Yi told reporters that the “limited and necessary self-defense 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 government claims sovereignty over most of the South China Sea , through which more than $5 trillion in global trade passes every year, and has been building runways and other infrastructure on artificial islands to bolster its case. Other regional powers, including Vietnam, the Philippines, Indonesia, Malaysia and Taiwan, have clashing claims to various parts of the sea.

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