WASHINGTON - US President Donald Trump threatened on Monday to impose a 10 percent tariff on $200 billion of Chinese goods, escalating a tit-for-tat trade war with Beijing.Trump said in a statement he had asked the US trade representative to identify the Chinese products to be subject to the new tariffs. He said the move would be in retaliation for China's decision to raise tariffs on $50 billion in US goods."After the legal process is complete, these tariffs will go into effect if China refuses to change its practices, and also if it insists on going forward with the new tariffs that it has recently announced," Trump said.