Valletta - EU leaders sought a plan to curb mass migration from Libya at a special summit in Malta on Friday that was overshadowed by the challenges of Brexit and Donald Trump.The 28 leaders are expected to back steps including helping the Libyan coastguard to cut the number of migrants making the dangerous sea crossing from north Africa to Italy.But they will also, without Prime Minister Theresa May, discuss the future of the bloc at a key turning point with Britain set to leave, and an increasingly difficult geopolitical situation with the new US administration.French President Francois Hollande lashed out at Trump, who has predicted that other countries will follow Britain out of the EU and branded the transatlantic NATO military alliance obsolete."It is unacceptable that there should be, through a certain number of statements by the president of the United States, pressure on what Europe should or should not be," Hollande said as he arrived at the summit.German Chancellor Angela Merkel meanwhile said the best way for the EU to deal with a US administration that seems ambivalent to Europe is to push forward with its own plans."I already said that Europe has its destiny in its own hands," Merkel told reporters as she arrived in Valletta. "That is why for me, talks about Europe are here in the foreground and not to deal with other parts of the world."Libya migration plan The key issue for Europe on Friday is tackling the Libyan migration route, having already largely shut the route to Greece over the Aegean through a controversial deal with Turkey.The leaders are expected to approve a new strategy to "break the business model" of traffickers who helped 181 000 mainly African migrants enter the EU via Libya and Italy last year.The plan involves funding and training the Libyan coastguard to make it better able to intercept migrant boats before they reach international waters, and helping neighbouring countries to close routes into Libya, according to a draft statement seen by AFP.On the eve of the Malta meeting, Italian Prime Minister Paolo Gentiloni and his Libyan counterpart signed a deal in Rome on tackling people smugglers in the North African country.That deal provides for the establishment of EU-funded but Libyan-run camps to house migrants pending their "voluntary return or repatriation" to their home countries.Italy committed to funding medical services for the camps.Rights groups however warned that sending boats back to Libya could result in children being sent back to squalid detention centres."We know that the situation of the refugees is dramatic in Libya. That is why we have to proceed as we did in the context with Turkey: prevent illegality, to stop the game of smugglers and traffickers and improve the situation of the refugees," said Merkel at the summit. Trump 'threat' to EU The talks will turn to international issues over lunch, with May, Merkel and Hollande all set to brief their colleagues on their contacts with Trump.May will say she won a guarantee of support for NATO from Trump and urge other EU leaders to meet commitments to spend two percent of GDP on defence, according to Downing Street.EU President Donald Tusk, who will chair the summit, warned in a letter to leaders ahead of the summit that Trump was a "threat" to the EU along with Russian aggression, an increasingly assertive China and domestic populism.But EU leaders also see the Trump administration as a chance for Europe to finally unify after Brexit and the eurozone crisis, and perhaps even take Washington's place in global politics and trade.After lunch, May will leave and the other 27 leaders will discuss a major declaration on the EU's future that they plan to unveil at a summit in Rome in March marking the 60th anniversary of the bloc's founding treaty.