European Commission President Jean-Claude Juncker (L) and European Council President Donald Tusk attend a press conference in Brussels, Belgium, on Dec. 14, 2018. European Union (EU) leaders Thursday made it clear to British Prime Minister Theresa May that renegotiation on the Brexit agreement is a non-starter. European leaders were gathering in Brussels for a customary two-day summit. High on the agenda were Brexit, multi-annual budget and migration. (Xinhua/Ye Pingfan)