China announced restrictions on drone exports to the United States and blacklisted six companies on Wednesday in response to trade sanctions imposed by Washington over forced labour and national security concerns. The move comes days after the United States imposed fresh tariffs on China and 59 other countries, adding to a series of recent trade measures. “China can only take necessary countermeasures in response, including strengthening export controls on drones, and their key components and technology to the US.” China and the United States spent much of last year embroiled in an escalating trade war but reached a truce when US President Donald Trump and his Chinese counterpart Xi Jinping met last October. The latest US tariffs against China and other trade partners however have threatened that truce, with Beijing warning Washington against waging a trade war.