The deepening world economic crisis and a possible spat over currency levels hung in the air as the United States and China sat down Thursday to discuss the future of their economic relations. US officials say Treasury Secretary Henry Paulson will press Beijing to let its yuan rise against the dollar to ease trade tensions at the two-day Strategic Economic Dialogue. American companies contend that China keeps the yuan undervalued, giving its exporters an unfair advantage and adding to its swollen trade surplus. But with China's exporters suffering, the yuan plunged Monday in government-controlled trading - a possible message to Washington to go easy on the issue. "The signal China sent on Monday is: We also have our own political problems and issues in a slowing economic environment," Frank F.X. Gong, chief Asia economist for JPMorgan Securities Ltd., said in a report to clients. State media said Thursday a rapid rise of the Chinese currency would harm the global economy further as it would hurt Chinese exports and increase unemployment.