The Saturday Profile
By JANE PERLEZ

HONOLULU — He has called Chinaprovocative and expansionist,” accusing it of “creating a Great Wall of sand” and “clearly militarizing” the disputed waters of the Western Pacific. “You’d have to believe in a flat earth to think otherwise,” he said in one appearance before Congress.

These are the words of the American commander in charge of military operations in the Asia-Pacific region, Adm. Harry B. Harris Jr., who has turned heads — and caused headaches — in Beijing as well as in Washington with language starker than any coming from his commander in chief, President Obama.

Admiral Harris makes no apologies for his candor, which has unsettled a more cautious White House. As China builds militarily fortified islands in the South China Sea, a strategic waterway long dominated by the United States, it is his job, he says, to talk to Congress, the American public and allies abroad about the threat.

“There is a natural tension between elements of the government and the chain of command, and I think it’s a healthy tension,” he said during an interview in his office, perched high above Pearl Harbor. “I’ve voiced my views in private meetings with our national command authorities. Some of my views are taken in; some are not.”

For the Chinese, Admiral Harris, 59, is not only a tough talker. He was born in Japan, the son of a Japanese mother and an American father who was a chief petty officer in the American Navy. The Chinese have zeroed in on his ethnicity as a mode of attack.

“Some may say an overemphasis on the Japanese background about an American general is a bit unkind,” Xinhua, the official Chinese news agency, wrote. “But to understand the American’s sudden upgraded offensive in the South China Sea, it is simply impossible to ignore Admiral Harris’s blood, background, political inclination and values.”

The derogatory comments had two goals, the admiral said. First, they were meant to show that the Pacific Command was “disconnected from the rest of government,” an idea that was “completely untrue.”

Second, they seemed intended to tarnish him. “You know when I am described as a Japanese admiral it’s not true. I am not sure why they have to have an adjective in front of admiral.”

When his family moved back to rural Tennessee, his mother refused to teach him Japanese, insisting that her son was 100 percent American. In that vein, the admiral does not make much of the fact that he is the first Asian-American to be appointed a combatant commander.

That insistence on his American identity makes the Chinese comments particularly galling to him. “In some respects, they try to demonize me, and that’s really ugly,” he said. “I think in a lot of ways the communications that come out of the Chinese public affairs organ, they are tone deaf and insulting.”

Interactive Feature | What China Has Been Building in the South China Sea China has been feverishly piling sand onto reefs in the South China Sea, creating seven new islets in the region and straining already taut geopolitical tensions.

A United Nations tribunal in The Hague is expected to rule soon on a case brought by the Philippines that could make China’s recent fortifications on islands in the South China Sea illegal. The panel could declare Beijing’s claim over most of the South China Sea, which stretches from the coast of China to the beaches of Southeast Asian nations, invalid.

The decision is widely expected to be unfavorable for Beijing, with potentially sharp consequences for the increasingly brittle relationship between China and the United States.

How boldly China reacts to the ruling is a major concern for Admiral Harris, whose task is to recommend military options should China push forward, either in the short or longer term, with its efforts to control a waterway through which trillions of dollars in trade, including oil and gas, passes every year.

Chinese military commentators have said China plans to make the Scarborough Shoal, an atoll Beijing grabbed from the Philippines four years ago, into a fortress. Only 120 miles from the Philippine coast, it would be a potential threat to an American ally. Beijing could also declare an air defense zone over parts of the South China Sea, forcing civilian airliners to make long and expensive detours to avoid risking encounters with the Chinese Air Force.

The stakes are so high that Mr. Obama warned the Chinese leader, Xi Jinping, during their recent meeting in Washington not to move on the Scarborough Shoal or invoke an air defense zone, said an American official who was briefed on the details of the encounter and spoke anonymously because of the diplomatic sensitivities.

Neither side wants conflict over specks in the sea. But the possibility has to be considered, and Scarborough Shoal is now the place Pentagon officials say the United States might take a stand.

The chairman of the Joint Chiefs of Staff, Gen. Joseph F. Dunford Jr., recently asked Admiral Harris just that question. In a conversation overheard by a reporter while the two men chatted at the Pentagon, the admiral’s answer was indistinct.

Asked later — war or not over the Scarborough Shoal — the admiral chuckled.

“It is good that my voice is low,” he said, popping a Coca-Cola as he sat on a couch in his expansive office. “I will say I’m a military guy. I look through the lenses darkly, and that’s what I’m paid to do.”

To defend American interests, he said, “I have to do it with the tools I have, and they are military tools, and they are great tools.”

“In the China piece, we just have to be ready for all outcomes from a position of strength,” Admiral Harris said, “all outcomes whether it is Scarborough, South China Sea in general, or some cyberattack.”

He said he was worried not so much about miscalculations in the South China Sea between the Chinese military and the forces of other countries. “I view them as a professional military.” The bigger risk, he said, is a clash caused by China’s paramilitary ships that could bring American forces to bear in defense of American allies.