BERLIN, Jan 8 (Reuters) - German President Frank-Walter Steinmeier has strongly criticised U.S. foreign policy under President Donald Trump and urged the world not to let the world order disintegrate into a "den of robbers" where the unscrupulous take what they want. In unusually strong remarks, which appeared to refer to actions such as the ousting of Venezuela's President Nicolas Maduro at the weekend, the former foreign minister said global democracy was being attacked as never before. Although the German president's role is largely ceremonial, his words carry some weight and he has more freedom to express views than politicians....