President Bush engaged in high-stakes talks Thursday with Chinese President Hu Jintao, the leader of one of the world's fastest-growing economies and one of its most formidable military powers. Bush said before the session that he would express both encouragement and concern to Hu. The two leaders, meeting on the sidelines of an Asia-Pacific economic summit, were expected to talk about an hour. Bush and his aides said he was eager to talk to Hu about increasing trade and climate controls and to express satisfaction with Beijing's role in pressing North Korea to agree to disavow nuclear weapons. But he was also ready to discuss product-safety issues following a rash of recalls in the United States, and to register his worries about China's exchange rate policies. Bush was to urge the Chinese leader to be more aggressive on Iran, raise the issue of jailed dissidents, press Hu on the humanitarian crisis in Darfur and on the treatment of the Dalai Lama, administration officials said. He may even bring up unsubstantiated reports that China's military has hacked into Pentagon computers.