BEIJING — A U.S. warship sailed within 12 miles of one China’s largest artificial islands Tuesday, part of a continuing effort by the Pentagon to demonstrate that the United States remains undeterred by the rapid Chinese military buildup in the South China Sea.

The presence of the USS William P. Lawrence, an Arleigh Burke-class guided-missile destroyer, prompted the Chinese military to scramble three fighter jets that monitored the destroyer, along with three Chinese ships, until the American vessel left the area.

“This operation demonstrates, as President Obama has stated, that the United States will fly, sail, and operate wherever international law allows,” said Cmdr. Bill Urban, a Pentagon spokesman. “That is [as] true in the South China Sea as in other places around the globe.”

The Lawrence passed near Fiery Cross Reef in what the Pentagon calls a freedom of navigation operation and exercised its “right of innocent passage,” according to Urban. The Wall Street Journal was the first to report on the operation. The vessel was not conducting military maneuvers and was allowed to sail near the reef under international maritime law, U.S. officials said.

Two years ago, Fiery Cross Reef was little more than a cluster of rocks jutting out of the water, but in recent months the Chinese have built it into a military facility, complete with a runway, helicopter landing areas and a port. The installation is one of more than a half-dozen Chinese-developed islands in the disputed Spratly Islands.

According to the Chinese Foreign Ministry, the U.S. destroyer entered the area without China’s permission.

“The American naval vessel threatened China’s sovereignty, security and interests, and it harmed the safety of the people and facilities in the island, damaging regional stability,” Lu Kang, a spokesman for the Foreign Ministry, said in a regularly scheduled news conference. “As we have stressed over and over again, China firmly opposes such behavior and we will take necessary measures to safeguard China’s sovereignty and territory.”

The Chinese Defense Ministry said later Tuesday that the equipment stationed on Fiery Cross is defensive in nature and accused the United States of militarizing the South China Sea with its repeated patrols in the area.

The U.S. operation came a day after the people of the Philippines went to the polls to elect a new president and just ahead of Obama’s visit to Vietnam later this month. Both the Philippines and Vietnam have laid claim to Fiery Cross, as has Taiwan.

Tuesday’s voyage marks the third freedom of navigation operation since last fall. In January, the USS Curtis Wilbur passed near the Paracel Islands, and in October the USS Lassen did the same near Subi Reef. Both the Wilbur and Lassen are destroyers.

Adm. Scott Swift, the top officer overseeing the Navy’s Pacific Fleet, said in a recent interview that the United States needs to be thoughtful, consistent, firm and patient about how it demonstrates freedom of navigation in the region. In the past year, it has challenged maritime claims in the region not only by China, but also by Taiwan, Vietnam and the Philippines, according to a Pentagon report released last month.

“It’s not that we need to drive right at these claims and challenge them in the starkest possible way,” Swift said. “The subtleties have as much impact as something that is more apparent, brash, kind of in-your-face. And I think that at this time of increased tensions, we need to be thoughtful about that.”

In recent weeks, the United States has sent warplanes to nearby Scarborough Shoal, a chain of coral reefs near the Philippines that China seized in 2012. The increased activity in both the Spratly Islands and near Scarborough Shoal comes as a panel of jurists at a United Nations-appointed tribunal in The Hague deliberates on whether China can legally claim the area around the disputed islands in the South China Sea as territorial waters.

Gibbons-Neff and Dan Lamothe contributed to this report from Washington. 

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