BRUSSELS (AP) — British Prime Minister Theresa May will hold her first talks with European Union leaders and will tell them that the U.K.'s decision to leave the bloc is irreversible.

May will make a short address to the 27 other EU leaders over dinner Thursday night, affirming that she will trigger the two-year exit process before the end of March.

European Council President Donald Tusk, chairing the two-day EU summit in Brussels, won't invite debate over the move.

It's the first time a member state has ever signaled it will leave the bloc.

The summit starts with talks on migration. The leaders will also discuss thorny relations with Russia. Friday's talks will focus on trade, notably the roadblock on agreeing an EU-Canada trade pact.