Slovakia's Prime minister Robert Fico delivers a statement after the European Union Summit of 27 Heads of State or Government in Bratislava, Slovakia on September 16, 2016. The 27 leaders -- minus British Prime Minister Theresa May -- gathered at Bratislava's towering castle overlooking the River Danube, determined to respond to the challenges of mass migration, security, globalisation and a stuttering economy. / AFP PHOTO / StringerSTRINGER/AFP/Getty Images

European Council President Donald Tusk delivers a statement after the European Union Summit of 27 Heads of State or Government in Bratislava, Slovakia on September 16, 2016. The 27 leaders -- minus British Prime Minister Theresa May -- gathered at Bratislava's towering castle overlooking the River Danube, determined to respond to the challenges of mass migration, security, globalisation and a stuttering economy. / AFP PHOTO / StringerSTRINGER/AFP/Getty Images

Latvia's Prime minister Maris Kucinskis speaks to journalists after European Union Summit of 27 Heads of State or Government in Bratislava, Slovakia on September 16, 2016. The 27 leaders -- minus British Prime Minister Theresa May -- gathered at Bratislava's towering castle overlooking the River Danube, determined to respond to the challenges of mass migration, security, globalisation and a stuttering economy. / AFP PHOTO / VLADIMIR SIMICEKVLADIMIR SIMICEK/AFP/Getty Images

German Chancellor Angela Merkel delivers a joint statement with the French President after the European Union Summit of 27 Heads of State or Government in Bratislava, Slovakia on September 16, 2016. The 27 leaders -- minus British Prime Minister Theresa May -- gathered at Bratislava's towering castle overlooking the River Danube, determined to respond to the challenges of mass migration, security, globalisation and a stuttering economy. / AFP PHOTO / JOE KLAMARJOE KLAMAR/AFP/Getty Images

(L to R) Slovakia's Prime minister Robert Fico, President of the European Council Donald Tusk and European Commission President Jean-Claude Juncker deliver a joint statement after the European Union Summit of 27 Heads of State or Government in Bratislava, Slovakia on September 16, 2016. The 27 leaders -- minus British Prime Minister Theresa May -- gathered at Bratislava's towering castle overlooking the River Danube, determined to respond to the challenges of mass migration, security, globalisation and a stuttering economy. / AFP PHOTO / StringerSTRINGER/AFP/Getty Images

German Chancellor Angela Merkel delivers a joint statement with the French President after the European Union Summit of 27 Heads of State or Government in Bratislava, Slovakia on September 16, 2016. The 27 leaders -- minus British Prime Minister Theresa May -- gathered at Bratislava's towering castle overlooking the River Danube, determined to respond to the challenges of mass migration, security, globalisation and a stuttering economy. / AFP PHOTO / JOE KLAMARJOE KLAMAR/AFP/Getty Images

President of the European Council Donald Tusk (R) and Slovakia's Prime minister Robert Fico (L) deliver a joint statement after the European Union Summit of 27 Heads of State or Government in Bratislava, Slovakia on September 16, 2016. The 27 leaders -- minus British Prime Minister Theresa May -- gathered at Bratislava's towering castle overlooking the River Danube, determined to respond to the challenges of mass migration, security, globalisation and a stuttering economy. / AFP PHOTO / StringerSTRINGER/AFP/Getty Images

French President Francois Hollande (C,L) and German Chancellor Angela Merkel leave after delivering a joint statement after the European Union Summit of 27 Heads of State or Government in Bratislava, Slovakia on September 16, 2016. The 27 leaders -- minus British Prime Minister Theresa May -- gathered at Bratislava's towering castle overlooking the River Danube, determined to respond to the challenges of mass migration, security, globalisation and a stuttering economy. / AFP PHOTO / STEPHANE DE SAKUTINSTEPHANE DE SAKUTIN/AFP/Getty Images