The state of Iowa signed a cooperation agreement with China's Ministry of Commerce on Thursday that will strengthen ties and enhance trade between the state and the country, The Des Moines Register reported. Also, the Chinese agreed to buy $100 million worth of U.S. soybeans. Iowa is one of only three areas, including California and Chicago, to sign such a memorandum with the Chinese Ministry of Commerce, and Debi Durham, Iowa's economic development director, told the Register that the agreement is a consequence of a Feb. 2012 visit to Iowa President Xi Jinping.