Greer urges G20 to back Trump tariff agenda, takes aim at China ↧ ↧ Greer urges G20 to back Trump tariff agenda, takes aim at China US Trade Representative Jamieson Greer on Wednesday called for G20 major economies to refrain from coercive actions ​on food trade, tackle industrial overcapacity and re-examine the prevailing post-World War Two tariff system.