EU leaders are meeting in Brussels on June 28-29 to discuss some of the 28-member bloc's most pressing issues, including the long-standing debate over migration, trade, the eurozone, and the negotiations for Britain's leaving the European Union in March 2019 -- the so-called Brexit process.
Continued disagreement over migration within the bloc could further entrench already deep fault lines and threaten EU unity.
"The stakes are very high. And time is short," European Council President Donald Tusk warned in a letter addressed to the leaders.
Tusk proposed that EU leaders agree to three initiatives on migration -- setting up regional disembarkation platforms outside Europe; creating a dedicated budget to fight illegal migration; and stepping up cooperation with countries of origin and transit.
The summit comes as German Chancellor Angela Merkel is facing intense pressure at home from Interior Minister Horst Seehofer, the head of Merkel's junior coalition partner.
Seehofer has given Merkel a deadline until the end of the month to reduce the number of asylum seekers entering Germany or risk a government split.
In an address to German lawmakers ahead of her departure for Brussels, Merkel defended her 2015 decision to open Germany's doors to 1 million migrants as a necessary measure to help its neighbors.
But Merkel said that, with falling migrant numbers, the tighter immigration controls of before 2015 must be reestablished.
"Europe faces many challenges, but that of migration could become the make-or-break one for the EU," she told parliament.
Italy's new government has also reopened the debate about sharing the burden of migration within the bloc after blocking port entry to two rescue boats carrying migrants in the past two weeks, while also calling for a "radical change" to the EU's migration policy.
The summit will also discuss trade after U.S. President Donald Trump's recent decision to impose tariffs on steel and aluminum products coming from the EU and his threat to impose levies on cars as well.
EU leaders will analyze the ongoing negotiations over Britain's exit from the bloc, and are expected to urge Britain to provide more clarity over the details of a future relationship.
Participants will also discuss ways to reform the bloc's monetary union to make it more resilient against shocks, and will also address cooperation between the EU and NATO.