President of the European Commission Jean-Claude Juncker (L), President of the European Council Donald Tusk and Slovakia's Prime minister Robert Fico arrive for 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

Poland's Prime minister Beata Szydlo speaks during his press conference 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

Poland's Prime minister Beata Szydlo speaks during his press conference 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

President of the European Commission Jean-Claude Juncker (L), President of the European Council Donald Tusk and Slovakia's Prime minister Robert Fico arrive for 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

JOLIET, IL - SEPTEMBER 16: Michael McDowell, driver of the #95 Thrivent Financial/TMNT Donatello Chevrolet, speaks to the press prior to practice for the NASCAR Sprint Cup Series Teenage Mutant Ninja Turtles 400 at Chicagoland Speedway on September 16, 2016 in Joliet, Illinois. (Photo by Kena Krutsinger/Getty Images)

President of the European Council 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

Austria's Chancellor Christian Kern speaks during his press conference 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

(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