China on Thursday defended its decision to hike tariffs on some US car imports, and challenged the United States to bring the case to the World Trade Organization if Washington begged to differ. \"We need to differentiate between protectionism and normal trade remedies,\" Chinese Commerce Minister Chen Deming told journalists on the sidelines of the WTO ministerial conference. \"China according to WTO rules ... conducted in an open manner and rule-based manner investigations into US car imports in China and decided to impose anti-dumping and countervailing measures,\" he said. \"This is in line with WTO rules and not a form of protectionism. \"If anyone begs to differ, the best solution is to ask the WTO experts to rule,\" said Chen, adding that China will respect the trade watchdog\'s verdict. The new tariffs to be applied for two years to passenger cars and sports utility vehicles with engine capacities of 2.5 liters or more took effect on the opening day of the WTO ministerial conference. The decision will affect vehicles produced by General Motors, Chrysler Group, BMW Manufacturing, Mercedes-Benz US International, American Honda Motor and Ford Motor. At the open of the Geneva meeting, trade ministers from across the world warned that protectionism is a growing threat as the global economy falters and could cost hundreds of billions of dollars (euros).