In recent decades, Vietnam has distinguished itself several times as a nation unafraid to stand up to its larger and far more powerful neighbor to the north. From the border conflicts of the 1970s and ’80s to the passage in 2012 of the “Law on the Sea” resolution, Hanoi has demonstrated its willingness to resist Beijing. But last month, in a sign of the shifting power balance between China and the United States, Vietnam yielded to Beijing’s intimidation.

The capitulation involved Talisman Vietnam, a subsidiary of Spanish energy company Repsol. Back in mid-June, the Vietnamese government gave Talisman authorization to drill in a gas reservoir in block 136-03 of the South China Sea. That location is near the border, but within Vietnam’s exclusive economic zone. As made plain by the United Nations Convention on the Law of the Sea (unclos), Vietnam was entirely within its rights to authorize this drilling.

But China was not comfortable with the activity.

The Chinese apparently believe that the Spratly Islands, near this drilling location, are entitled to their own exclusive economic zone—even though the Permanent Court of Arbitration at The Hague specifically ruled otherwise in a landmark decision last year.

China has little regard for international laws that are not consistently enforced, so the leadership in Beijing dispatched the Central Military Commission’s vice chairman to demand that Vietnam stop drilling in block 136-03. When the request was denied, Beijing withdrew from a China-Vietnam border security meeting. When Vietnam continued to drill, China summoned Vietnam’s ambassador in Beijing to inform him that military action was on the table if Talisman didn’t stop drilling.

If the Vietnamese leadership had faith in American support and in U.S. assurances to uphold international law, they would have continued to ignore China. But Vietnam’s politburo had no such faith. They felt that the U.S. could not be relied upon to come to Vietnam’s assistance if a confrontation with China were to erupt, so they capitulated. The Vietnamese government ordered Talisman to pack up their entirely legal drilling project and to clear out of the area. Repsol confirmed on August 2 that it suspended drilling, after having invested some $27 million into the project.

Gregory Poling of the Southeast Asia program at the Center for Strategic and International Studies said when it comes to the South China Sea, the Vietnamese leaders “can try their best to deter the Chinese …. But when the Chinese push back hard, like they just did, the Vietnamese are out on a limb all by themselves.”

David Shear, former U.S. ambassador to Vietnam, said Hanoi’s decision to kowtow to Beijing was partly because of the Trump administration’s “inattention” to the region. “This is a setback for the rules-based order and for our interests,” he said.

Writing for Foreign Policy, Bill Hayton said it would not have been difficult for the Trump administration to uphold international law in this situation: “[I]t wouldn’t have taken much: a statement or two about the rules-based order and the importance of abiding by unclos, some coincidental naval exercises during the weeks of the drilling, perhaps even some gunnery practice in the region of Block 136-03 and a few quiet words between Washington and Beijing. ‘Forward-deployed diplomacy,’ as it used to be called.”

But there was nothing like that from the United States, so Vietnam caved to the pressure.

This capitulation demonstrates the vast amount of influence the U.S. has lost in the South China Sea. It shows that, whatever international law may say, in the South China Sea, Beijing is king. China writes the rules, and decides who can and can’t drill, and what locations are acceptable or unacceptable for various economic activities.

For more on this topic, read “Congratulations, Beijing. The South China Sea Is Now Yours.”