Chinese President Hu Jintao and Vice President Joseph R. Biden Jr. walk the red carpet upon Mr. Hu's arrival Tuesday at Andrews Air Force Base, Md., for the start of a state visit. China's trade with Iran will be one of many thorny issues President Obama will likely raise with Mr. Hu. (Associated Press)

Photo by: Evan Vucci

Chinese President Hu Jintao and Vice President Joseph R. Biden Jr. walk the red carpet upon Mr. Hu's arrival Tuesday at Andrews Air Force Base, Md., for the start of a state visit. China's trade with Iran will be one of many thorny issues President Obama will likely raise with Mr. Hu. (Associated Press)