WASHINGTON (AP) — A visit by China's top diplomat, intended to show growing U.S.-China cooperation, instead highlighted political differences between the two world powers as Washington spoke out about democracy protests gripping Hong Kong.

Foreign Minister Wang Yi stopped in Washington after attending the U.N. General Assembly last week. He met Wednesday with his counterpart John Kerry and got face time with President Barack Obama, who joined Wang's discussions with National Security Adviser Susan Rice at the White House.

The U.S. officials repeated the usual bromides about deepening ties, and they discussed Obama's Nov. 10-12 visit to China, when it hosts an economic summit of Asia-Pacific leaders.

But Kerry, standing alongside Wang, also spelled out U.S. support for electoral change in the Chinese territory of Hong Kong. Wang said that was none of Washington's business.

"Hong Kong affairs are China's internal affairs," he told reporters. "All countries should respect China's sovereignty."

The diplomatic jousting underlined how the U.S. and China remain poles apart on issues related to democracy, human rights and territorial disputes in Asia's seas, even as they cooperate in other areas, like climate change.

That could in one sense be seen as positive: Despite an emerging military rivalry and mutual suspicion, they are able to publicly discuss what divides them without it brewing into a storm.

Using Beijing's favored phrase, Kerry said the U.S. and China "want to show a new model of relations."

"The common interests between us are far greater than our differences," Wang said.

But that doesn't mean they can find common ground on the issues that separate them, and the situation in Hong Kong is particularly sensitive to China, which faces an unusual challenge to its authority.

China took control of the former British colony in 1997 after agreeing to let Hong Kong have more freedoms than the mainland.

Protesters say Beijing is reneging on a promise that Hong Kongers would be allowed to choose their own leader starting in 2017, after it decided all candidates must be approved by a committee of mostly pro-Beijing local elites.

Tens of thousands of people have rallied since late last week, and protest leaders are warning they may occupy several important government buildings unless Hong Kong's current chief stands down by Thursday.

Kerry urged Hong Kong authorities to exercise restraint and respect for the right of the protesters to express their views peacefully. Wang said no country would "allow those illegal acts that violate public order." He said Hong Kong's administration could handle the situation.

The protesters have looked to the U.S. for moral support. The White House responded Tuesday to an online petition, which garnered 196,000 signatures, for Obama "to press the Chinese government to honor its promise of democratic elections to the Hong Kong citizenry."

In its response, the White House said the legitimacy of Hong Kong's leader would be "greatly enhanced" if there was "a genuine choice of candidates representative of the voters' will." To get a response, a petition has to gain 100,000 signatures.

Richard Bush, a China expert at the Brookings Institution think tank in Washington, said the response went beyond past U.S. statements and implied that Beijing's electoral plan would not confer legitimacy.

But he said Washington won't want to feed propaganda out of Beijing that the U.S. is stimulating the protests and will be hoping the situation is resolved peacefully. Meanwhile, Beijing won't want the November summit, where Obama is due to meet with China's President Xi Jinping, to be overshadowed by a crackdown on protesters.

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