BANGKOK (AP) — A look at recent developments in the South China Sea, where China is pitted against smaller neighbors in multiple disputes over islands, coral reefs and lagoons in waters crucial for global commerce and rich in fish and potential oil and gas reserves:

WHITE HOUSE ON COLLISION COURSE WITH CHINA?

The new U.S. administration is heating up rhetoric over the South China Sea with a promise to challenge China’s occupation of disputed islands. Beijing is responding cautiously, appealing for calm and direct negotiations involving claimants.

White House Press Secretary Sean Spicer said “the U.S. is going to make sure that we protect our interests there.” His comments came just weeks after President Donald Trump’s pick for secretary of state, Rex Tillerson, caused some consternation when he told his Senate confirmation hearing that the U.S. should deny China access to its seven man-made islands.

“So it’s a question of if those islands are in fact in international waters and not part of China proper, then yes, we’re going to make sure that we defend international territories from being taken over by one country,” Spicer said. Pressed on whether that means physically preventing China from accessing the islands, he refused to answer, saying “I think as we develop further, we’ll have more information on that.”

China immediately responded, with Foreign Affairs spokeswoman Hua Chunying saying the U.S. is not a party to the disputes and should stay away. She again insisted that China has “indisputable sovereignty” over the South China Sea and is committed to safeguarding it. She said China preserves freedom of navigation in those waters — a concern the U.S. has repeatedly challenged as it stepped up its military presence in the region.

The comments at the regular briefing in Beijing were followed up by the most senior Foreign Affairs spokesman on NBC News, who said “there might be a difference” of opinion over the sovereignty of these islands, “but it’s not for the United States” to get involved in.

“That’s not international territories, that’s Chinese territories,” said Lu Kang. “Countries have already come back to the original agreement that maybe for the time being we could set aside those sovereign disputes, and focus on some joint developments, and working together to maintain the peace and stability in this region.”

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ANALYSTS WORRY ABOUT ESCALATION

The references by U.S. officials to blocking China’s access to artificial islands have caused concern among analysts about a potential for military escalation in the South China Sea.

“If the U.S. takes actions against China’s moves to protect their own sea territories, it may result in a serious military confrontation,” said Sun Hao, an international relations expert at the China Foreign Affairs University in Beijing.

Teng Jianqun, a scholar at the China Institute of International Studies, said he didn’t believe the U.S. would follow through on the threat of a blockade, saying “it’s like announcing war. That would be ridiculous.”

“Both Tillerson and Spicer seem to be trying to show China that the Trump administration will adopt a tougher approach on the South China Sea, but it’s evident that they haven’t yet developed a policy,” said Bonnie Glaser, senior adviser for Asia at the Center for Strategic and International Studies. She said the Trump administration needed to send “clear, consistent” signals to China.

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U.S. TO CONSTRUCT FACILITIES IN PHILIPPINES

The Philippines, the only U.S. defense treaty ally among the six claimants in the South China Sea, said the U.S. military will soon commence construction of facilities to accommodate troops and equipment inside Philippine army bases.

The five locations for U.S. troops were chosen in a 2014 defense agreement and include air bases facing the South China Sea. China has criticized the U.S. military presence in the Philippines.

Defense Secretary Delfin Lorenzana said President Rodrigo Duterte, who has had a testy relationship with Washington and has mended ties with Beijing, was aware of the impending construction.

Still, Lorenzana said his country should maintain neutrality as he expressed fear of getting caught between the U.S. and China should Washington press ahead with blocking China’s access to Beijing-controlled islands.