EU President Donald Tusk has warned that the European Union could break down completely after Brexit, at a summit to mark the organisation’s 60th anniversary. Tusk called for leadership to steer Europe out of crisis at the special summit in Rome, which is being held today to mark the anniversary of the bloc’s founding treaties. ‘Prove today that you are the leaders of Europe, that you can care for this great legacy we inherited from the heroes of European integration 60 years ago,’ former Polish prime minister Tusk said in a speech. ‘Europe as a political entity will either be united, or will not be at all.’ Twenty-seven leaders are meeting without British Prime Minister Theresa May to celebrate the signing of the European Union’s founding Treaty of Rome on March 25, 1957. Britain’s decision to leave the bloc is one of a host of crises facing an increasingly divided EU, along with migration, the economy, terrorism and the rise of populist and nationalist parties.