US President Barack Obama and Chinese President Hu Jintao emerged from hours of intense talks Tuesday determined to marshal their combined clout on crucial issues, but still showing divisions over economic, security and human rights issues that have long bedeviled the two powers."The relationship between our two nations goes far beyond any single issue," Obama said in a joint appearance with Hu that followed about 2 1/2 hours of private conversations.Both leaders spoke in bold terms of the growing relationship between the countries and emphasized cooperation on the economy, climate change, energy and the nuclear threats of Iran and North Korea.But in those areas and others, there remained differences that underscored that tensions would hardly be erased in Obama's first, high-profile visit to China. Obama spoke at length about the nations' joint interests and said, "I do not believe that one country's success must come at the expense of another."Obama and Hu said they agreed on restarting the collapsed six-nation effort to rid North Korea of its nuclear programs. The Chinese said the effort was essential to "peace and stability in northeast Asia."Beijing has supported sterner sanctions against Pyongyang for its continued nuclear weapons program. And, as North Korea's last major ally and a key supplier of food and energy aid, China is a partner with major leverage in six-nation talks with the North over the issue.On Iran, where the US needs China's clout to help pressure the nation to give up any of its own nuclear weapons programs, Obama spoke with sterner language than Hu."Iran has an opportunity to present and demonstrate its peaceful intentions, but if it fails to take this opportunity, there will be consequences," the US president said. Hu made no mention of consequences, saying the Iran conflict is important to resolve through negotiations.China has significant economic ties with Iran, and Beijing has appeared less willing to endorse a tougher approach to restrict Teheran's uranium enrichment and suspected pursuit of atomic bombs.In a minor step forward, Obama announced that the governments will reconvene their on-again, off-again human rights dialogue early next year. Previous rounds have fallen casualty to disputes over arms sales to Taiwan and other issues.Hu expressed disappointment with the Obama administration over its decision to impose punitive tariffs and duties on imports of Chinese tires and steel pipes. "Our two countries need to oppose and reject protectionism in all its manifestations in an even stronger stand," Hu said.The Chinese president also called on the US to respect China's "core interests" - code for ending support for Taiwan and for the Dalai Lama, in his Tibetan government-in-exile.On climate, Obama said the United States and China are looking for a comprehensive deal during next month's climate change summit that will "rally the world."Obama said the goal at the Copenhagen meeting should be an agreement that has "immediate operational effect," not just a political declaration. As the world's two largest consumers and producers of energy, Obama said the United States and China must play a key role in negotiating an agreement.Obama said China has helped the United States pull out of the worst recession in a generation. He said a revised economic approach will help increase US exports and create jobs while helping bring about higher living standards in China.Obama came to China seeking help with an array of global troubles. He and Hu sought to strike a balance between trading partners and competitors during Obama's trip to China during his Asia tour.A day before, Obama prodded China about Internet controls and free speech during a forum with students in Shanghai. His message was not widely heard in the country; his words were drastically limited online and shown on just one regional television channel.He also suggested that China, now a giant in economic impact as well as territory, must assume a larger role on the world stage - part of "burden of leadership" it shares with the United States.Eager to achieve a successful summit, the two leaders avoided spats on economic issues. With America's budget deficit soaring to a yearly record of $1.42 trillion, China is the No. 1 lender to Washington and has expressed concern that the falling price of the dollar threatens the value of its US holdings.In the US, American manufacturers blame China's own low currency value for contributing to the loss of 5.6 million manufacturing jobs over the past decade. During that time, America's trade gap with China has soared.With sightseeing in Beijing's Forbidden City sandwiched in between their talks, the two leaders' day was to end at a lavish state dinner in Obama's honor.Topmost on Obama's ambitious agenda with Hu is the so-far elusive search for global agreement on a new climate change pact, stymied by disagreement between rich nations like the US and developing nations such as China. Wealthier countries want legally binding greenhouse-gas reduction targets for themselves as well as for energy-guzzling developing nations such as China, India and Brazil. Those poorer nations say they will set only nonbinding goals and they demand assistance to make the transition to harder targets.