Europe continues to face its greatest migration wave since the end of World War II. The majority of migrants are arriving from outside the continent, especially the Middle East and North Africa (MENA) but also the Sahel and, increasingly, Asia. In March 2017, Frontex, the EU’s frontier agency, warned that the number of people undertaking the Central Mediterranean crossing was on the rise. With the arrival of summer, the next wave of MENA migration into Europe is about to be unleashed.

A May 2017 German government report warned that up to 6.6 million people were clustered around the Mediterranean preparing to cross to Europe from Africa, awaiting favorable summer weather to launch to sea. Now that the Western Balkan migration route has been closed, Libya is fast becoming the main transition point, reportedly with 2.5 million migrants in North Africa waiting to cross by boat. Meanwhile, over 3 million remain stalled in Turkey, prevented from entering Europe by the EU’s March 2016 refugee deal with the Turkish government. The figures could be higher still: some estimates put the number of migrants preparing to enter Europe as high as 8–10 million.

The uninterrupted flow of migration into the EU has redefined Europe’s geostrategic position. Today, Europe’s Southern border runs deep into Africa along the Sahel and across the Middle East. Southern Europe in particular remains exposed and vulnerable to pressure from MENA migration flows, which have had two ripple effects.

The first has been the progressive atrophying of the EU’s Schengen system of passport-free travel, one of the greatest achievements of European integration. The second has been growing polarization among states across the continent, with fundamental and increasingly intractable divisions on the question of resettlement—especially between Germany and Central and Eastern Europe. Temporary border controls established in Europe in September 2015 did not provide much respite. Now, the proposed lifting of border controls within the EU is likely to accelerate migration flows.

Europeans’ initial calm, goodwill, and even enthusiasm for the new arrivals and manifest Willkommenskultur, or welcoming culture, have given way to growing public anger. In parallel, public confidence in European governments’ ability to deal with the crisis has rapidly declined.

The current EU debate on how to tackle the crisis seems to have bifurcated into two strands. On the one hand, the European Commission and some countries most impacted by migration, especially Germany, have made repeated demands for European solidarity on resettlement quotas. On the other hand, states that have been less affected, primarily in Central Europe, have made efforts to slow down the flow by closing off access routes, while others such as Italy have sent money to countries in the region to keep the migrants in place. Despite occasional indicators of success, especially in terms of assistance to transit states, the EU will likely be overwhelmed by the next migration wave, with surging numbers of migrants from deep inside Africa.

Migration continues to reorder domestic politics in Europe, as immigration fatigue sets in across the continent and national populist parties gain traction. No other issue drives political realignment in Europe more directly today than the growing public anger over governments’ inability to stop the flood, process applications in a timely manner, and return those whose asylum applications have been rejected. In election after election, challengers have threatened established political parties, and although anti-immigration parties have yet to prevail and their support fluctuates, they have managed to shrink the political middle ground in Europe.

MENA migration also fuels frictions between governments. Austria’s foreign minister recently demanded that Italy stop allowing illegal migrants to reach the Italian mainland, as this gives them a gateway to Europe. In July, the Italian foreign ministry responded by calling in the Austrian ambassador to complain after the Austrians threatened to deploy 750 military personnel to the Brenner Pass on the Austrian-Italian border.

Meanwhile, the governments of Hungary and Poland have been outspoken in their determination not to allow any migrants to be resettled on their territories. Opposition to the European Commission’s quota schemes for migrant resettlement remains strong across Central Europe.

These tensions have fractured the EU on immigration policy. Resentment has grown in those European countries that have borne the brunt of resettling the new entrants, especially Germany and Sweden but also Austria, Denmark, and, outside the EU, Norway. Some governments have made it clear that they are prepared to use their armed forces to prevent illegal migration into their countries.

A key factor in the current European debate on migration has been the initial decision to allow migrants to enter and be processed in Europe regardless of whether they can prove refugee status, even though the majority are economic migrants. If there is a solution to the current migration crisis, it lies in sealing the EU’s external borders and establishing a system to screen migrants outside Europe.

This would require a large commitment of resources as well as European military power to create areas where initial screenings could take place before migrants can enter Europe. Admittedly, this would be a massive task, as it would require the EU to engage both militarily and in terms of aid to transit countries on a scale not seen so far, beginning with breaking smuggling chains and stopping boats from leaving for the Mediterranean.

Europe is fast approaching a moment of truth about how such massive migration waves will impact the European project, intergovernmental relations, and the overall culture of tolerance that defined postwar democratic Europe. For more than two years, the migration crisis has splintered an already fragile EU consensus on immigration policy, with the blame game becoming ever more common. Finger pointing in Europe, especially against Germany for its decision to open its doors to a large number of migrants in 2015, has become an important variable in how the intra-EU politics of migration has unfolded.

But such accusations and counteraccusations will do nothing to address the crisis. Unless governments engage on a large scale at the source, the likely victim will be Europe’s already tenuous tolerance of immigrants. The clock is ticking.

Andrew A. Michta is the dean of the College of International and Security Studies at the George C. Marshall European Center for Security Studies. Views expressed here are his own.