Members to plan how to assist each other in event of attack as transatlantic alliance faces worst crisis in its history

Brussels officials will draw up a plan on how to use the EU’s little-known mutual assistance pact in the event of a foreign attack, as Donald Trump’s criticism of Nato intensifies.

EU leaders have agreed that the European Commission “will prepare a blueprint” on how the bloc will respond if the mutual assistance clause is triggered, according to Nikos Christodoulides, the president of Cyprus, who is hosting the talks.