UK Prime Minister Boris Johnson has warned that the worst is yet to come for Ukraine, but has encouraged fellow world leaders to come together in alleviating the damage spurred by Russia’s invasion. In an opinion piece penned in the New York Times, Johnson bemoaned the attacks by Russian troops. Johnson says it is no longer enough to express warm platitudes about the rules-based international order. The prime minister says they now have to have to actively defend Ukraine against a sustained attempt to rewrite the rules by force and other tools, such as economic coercion. “We are pleased to see…