In chaos theory, the flapping of butterfly wings can cause a hurricane on the other side of the world. This weekend, Ukraine experienced a butterfly moment. Donald Trump’s efforts to conceal the fact that he bought the silence of a porn star before the 2016 election landed him in court, facing charges that preoccupy him enough for congressional Republicans to reject his policy of prematurely ceding territory to Russia in return for peace in Ukraine. Kyiv will now get billions of dollars to buy the weapons crucial for it to defend against, and push back, the Russian advance. It is fitting that Mr Trump’s divisive appeasement has been defeated – for now – by a bipartisan defence of democracy.