President Trump has said that his foreign policy will be based on the principle of 'America First'. He's surrounded in the Oval Office by people who dispute the notion that the US has an obligation to maintain a stable international order. Some are hostile to the EU and attach little value to international institutions such as Nato and the United Nations. And now Donald Trump has his finger on the trigger of nearly 7000 nuclear warheads. Abi Austen travels to the US to find out what the Age of Trump means in practice for the rest of the world and asks: just how worried should we be?