European Union leaders open a two-day summit in Brussels Thursday to address everything from Britain's planned exit from the regional economic bloc to the resurging economy.

British Prime Minister Theresa May's remarks at the two-day meeting are expected to include reassurances about the futures of the three million citizens of other EU countries currently living in Britain.

Together with the future of more than 1 million British citizens living elsewhere in the EU, the issue is one of the major topics the two sides must agree on as part of negotiations that began earlier this week.

After May speaks Thursday night, the rest of the leaders will meet without her to discuss their side of the Brexit process that was triggered by a British referendum one year ago and is set to finish by the end of March 2019.

The EU summit will also tackle migration, renewing sanctions against Russia and efforts to combat online extremism.