WASHINGTON — Vice President Joe Biden said Wednesday that China's rise is good but its theft of U.S intellectual property must stop as the global powers held annual talks that signaled more cooperation on tackling climate change while underscoring their deep differences on human rights.

The gathering took place a month after the U.S. and Chinese presidents' summit in California that tried to set a positive tone in relations but also made clear Washington's growing anxiety about Chinese cybertheft.

"We both will benefit from an open, secure, reliable Internet. Outright cyberenabling theft that U.S. companies are experiencing now must be viewed as out of bounds and needs to stop," Biden said in his opening remarks at the State Department.

He cited the "emerging and continuing growth of the Chinese economy" as good news, with Beijing's rise "good for America and the world." Yet such progress, Biden said, "comes with some new international responsibilities."

In the first of two days of Cabinet-level discussions they talked about trade and investment barriers, and the nuclear program of North Korea, where the U.S. wants China to lean on its troublesome ally to disarm. Also on the agenda were territorial disputes in the East and South China Seas, where assertive Chinese behavior has unnerved its neighbors.

The most tangible outcome Wednesday was an announcement of new initiatives to reduce greenhouse gas emissions and air pollution. The two sides agreed to cooperate on cutting emissions from vehicles and coal combustion, and to promote more efficient use of energy in buildings, transport and industry. Implementation plans will be ready by October, the State Department said.

Secretary of State John Kerry returned from his wife's bedside in Boston and issued tearful thanks for the outpouring of good wishes for Teresa Heinz Kerry, hospitalized as she recovers from a seizure-like episode. He returned later Wednesday to Massachusetts, with deputy William Burns now taking his place at the talks.

The Chinese side was led by Vice Premier Wang Yang and State Councilor Yang Jiechi, who said U.S.-China relations had "reached a new starting point" after the June summit between President Barack Obama and President Xi Jinping.

"China will stay committed to reform and opening up," Yang Jiechi said, adding that his nation was committed to being a responsible player in the international system.

But he made only passing reference to cybersecurity as one of the "global challenges" that the U.S. and China should work together on. They have discussed it this week, but remain at odds over what is acceptable behavior in cyberspace. U.S. officials are resisting China's attempts to compare their concerns over U.S. surveillance for intelligence gathering — as revealed by National Security Agency leaker Edward Snowden — with American concerns about theft of intellectual property and proprietary business information.

Differences also came to the fore when Kerry made forceful comments to China on the importance of human rights to the United States, according to U.S. officials who briefed reporters about the closed-door exchanges, describing them as "lively."

In his public remarks, Yang said Beijing was willing to discuss human rights with the U.S. However Vice Premier Wang stressed that China — a one-party state intolerant of political dissent — won't accept views that "undermine our basic system."

China has also been reluctant to deepen military ties, which Biden stressed were important for avoiding the risk of confrontation between the two countries in the Pacific.

Despite those reservations, the two sides broached the sensitive issues of nuclear policy and missile defense for the first time in annual talks. China is concerned that U.S. moves to boost its capabilities in response to the emerging threat from North Korea are aimed at China too.

Another U.S. concern, the low value of China's currency and its impact on the skewed trade balance, has eased as the yuan has appreciated in value against the dollar. But the U.S. is still prodding Beijing to expedite economic reforms.

Biden said China needs to free its exchange rate, shift to a consumption-led economy instead of relying on exports and enforce intellectual property rights. He said the U.S. welcomes China's growth, but it should be based on international rules.

Treasury Secretary Jacob Lew urged China to "follow through decisively" on its economic reform commitments.

U.S. businesses and lawmakers want easing of barriers to American trade and investment, a roll back of subsidies for Chinese state-owned enterprises and progress on negotiations for a bilateral investment treaty.

China objects to security screening of its companies as they look to invest in the U.S.

In Congress, a Senate committee was examining China's biggest takeover of a U.S. company, a proposed $4.7 billion bid by Shuanghui International for pork producer American Smithfield Foods Ltd.

A bipartisan group of 15 senators has asked Lew to consider U.S. food security and food safety issues when the deal has a national security review. That could fuel China's suspicions that its companies are subject to tougher scrutiny than other foreign investors in America.