The summit is likely to be Theresa May's last before triggering Article 50
Taoiseach Enda Kenny will join other European leaders in Brussels today for an EU summit.
The European Council summit is supposed to project an image of unity among the member states ahead of the end of March and the EU's 60th anniversary.
Enda Kenny said: "Discussions on the future direction of Europe are [...] crucial, particularly as we respond to the various challenges we face.
"We must remain united at 27, focus on our core values that remain central to our peace and prosperity, and cooperate in areas where we agree and where Europe can add value," he added.
Today is likely to be British Prime Minister Theresa May's last summit before triggering Article 50, which will commence the Brexit process.
There will also be talks on migration and the single market, as well as the re-election of Donald Tusk as EU Council president.
Polish Prime Minister Beata Szydlo has written to other European leaders, seeking to oust Mr Tusk in a vote at the beginning of the summit.
Ms Szydlo has accused her countryman of interfering in domestic politics.
Mr Tusk, whose initial two-and-a-half-year term expires at the end of May, would be expected to play a key role in the Brexit negotiations and he believes he has the support of many EU leaders.
But the bitter row between former Polish prime minister Mr Tusk and Ms Szydlo's Law and Justice Party has led to Warsaw proposing a challenger for the job - Polish MEP Jacek Saryusz-Wolski.
The dispute will come to a head at the beginning of the summit, when EU leaders will vote on whether Mr Tusk should continue in the role until the end of November 2019.
Speaking ahead of today's summit, Mr Tusk said: "Negotiating the political and technical hurdles of Brexit will be our daily challenge. But there is also the work to chart a future course for the EU27."