Dutch Prime Minister Mark Rutte (L) and European Union's chief negotiator Michel Barnier talk during a round table meeting at a special Brexit summit in Brussels, Belgium, Nov. 25, 2018. (Photos: Xinhua)

Luxembourg Prime Minister Xavier Bettel (L) talks with European Council President Donald Tusk during a round table meeting at a special Brexit summit in Brussels, Belgium, Nov. 25, 2018.

German Chancellor Angela Merkel (C) greets with European Union's chief negotiator Michel Barnier (R) during a round table meeting at a special Brexit summit in Brussels, Belgium, Nov. 25, 2018.

The European leaders on Sunday endorsed the Brexit deal at the European Union (EU) summit, a major breakthrough since the lengthy Britain-EU Brexit negotiation started one and half years ago.

Austrian Chancellor Sebastian Kurz (L) and European Union's chief negotiator Michel Barnier are seen during a round table meeting at a special Brexit summit in Brussels, Belgium, Nov. 25, 2018.

Austrian Chancellor Sebastian Kurz, European Union's chief negotiator Michel Barnier, Italian Prime Minister Giuseppe Conte, French President Emmanuel Macron, European Council President Donald Tusk and Dutch Prime Minister Mark Rutte (from L to R) talk during a round table meeting at a special Brexit summit in Brussels, Belgium, Nov. 25, 2018.

European Union's chief negotiator Michel Barnier (2nd L) shakes hands with European Council President Donald Tusk (R) during a round table meeting at a special Brexit summit in Brussels, Belgium, Nov. 25, 2018.