The United States launched a challenge to Chinese tax exemptions for some locally produced aircraft, saying they discriminated against imported products. The request for consultations with China at the World Trade Organization over a value-added tax of 17 percent on imported planes is the first step in a process that could lead to trade sanctions. The U.S. Trade Representative said the tax was generally imposed on planes under 25 metric tons coming from overseas, while locally made planes such as state planemaker Commercial Aircraft Corp of China's (COMAC) ARJ21 jet were exempt. “China’s discriminatory, unfair tax policy is harmful to American workers and American businesses of all sizes in the critical aviation industry, from parts suppliers to manufacturers of small and medium-sized aircraft,” U.S. Trade Representative Michael Froman said in a statement. China had also failed to publish the tax exemptions, in an apparent breach of WTO transparency commitments, USTR said. China is keen to develop a successful commercial aircraft to rival those of Boeing and Airbus. The ARJ21, China's first locally built regional jet, is designed to compete against Brazil's Embraer SA and Canada's Bombardier Inc.