"Respecting the will of the British people we all recognized that the process of [Brexit] was in everyone's and especially in the UK's interests. Prime Minister Cameron undertook that the decision to trigger article 50 of the [Lisbon] treaty on the European Union would be taken by the new leadership in Britain," Tusk said at a press conference after the EU summit in Brussels.
According to Tusk, "Brexit means substantially lower growth in the UK with a possible negative spillover all over the world".
If the UK authorities need more time to formally announce the decision on Brexit, Brussels will have to wait, though it is not the best option for both sides, Tusk added.
According to the Article 50 of the Lisbon Treaty, each EU member state can leave the bloc. Aiming to start the process of leaving the European Union, a member state must formally inform Brussels about its intention and, then, launch negotiations on abandoning the bloc. All EU treaties become rendered void when a final agreement is achieved or – if not – two years after the country’s notification. A country that left the European Union may join it again through the same procedures as other candidates.