Not long ago the great cities of Europe were secure places of cultural strength. Today they are targets for ISIS and other terrorist organizations. Standing in solidarity with the citizens of Belgium, we mourn the indiscriminate slaughter of civilians in Brussels. On Tuesday, jihadists orchestrated coordinated bombings at the Brussels Airport and the city’s Baelbeek metro station, suicide assaults that murdered 31 people in a grim replay of the horrifying attacks in Paris.

The maelstrom of violence is a consequence of reckless open border policies and naïve assumptions about the potential for multicultural conversion to Western economic and political freedoms. Although this week’s bombings are probably retaliation for the capture of the mastermind of the suicide strikes in Paris, Brussels has long contended with a seedbed of warped Islamic aggression, particularly in its Molenbeek neighborhood.

Middle East conflict and the resulting humanitarian catastrophe prompted some European leaders to embrace well intentioned but misguided immigration postures that have contributed to the largest migrant crisis since World War II. Nations from Greece to Sweden are confronting capacity issues and now deadly security risks. No immigration system can remain just and orderly without robust border protection measures.

Contributing to the problem is the absence of a European myth—a romanticized vision of cultural and political tradition. The new narrative is that particular countries decreasingly matter. Supra-national entities like the European Union forge a new settlement of administrative conformity to deal with the pressures of globalization. Originally, the European Union arose from fears of past nationalist movements such as Fascism that ravaged and sacrificed the continent on the altar of ruthless ideology. The European Union serves to check this dark past while also facilitating commonalities in commerce, travel, and enhanced understanding. However, the limits of bureaucratic management are reached when identity and self-preservation is at stake.

Unfortunately, the very idea of Europe is disintegrating. To turn this around, the continent should regain a healthy instinct of nations that places an emphasis on the interests of peoples with a shared culture, history, and political traditions. The continent’s vibrancy depends on sustaining the dynamism of longstanding local difference while maintaining proper pride in the ideals that bind and animate wider Western civilization. Nothing exists in a vacuum. The lack of a bonding identity, complicated by clashing cultural values, has created Molenbeeks in other major European cities. Self-isolating Muslim communities can help perpetuate an environment of mutual misunderstanding and distrust, breeding alienation, resentment, and hostility. Genuine multiculturalism is difficult without enculturation among immigrant populations.

Thousands of Europeans have left the continent for the battlegrounds of Syria and Iraq. These radicalized fighters—passport holders hardened by war and dedicated to jihadist militancy—pose a serious security risk to their countries of origin in the West. Even some so-called Americans have joined the ranks of terrorist organizations that are metastasizing across the Middle East and North Africa. San Bernardino demonstrated that the United States is far from immune to the cancer of ISIS expansion.

Our nation for decades has shouldered a great burden in confronting havoc throughout the world. We will continue to lead the fight against extremism, but not alone. A general assumption that we will maintain the majority of the heavy lifting in combating regional terror—coupled with the lack of will among some of our allies—has created a status quo that is unsustainable.

As we recover from the shock of the bombings in Brussels, we must reclaim a central principal. Europe must fight. Complacency is no longer possible. The combined effects of a drifting European identity and a lack of enculturation, further compounded by a migrant crisis, must be confronted with reason and resolve to keep Europe and the world safe. Only through this approach will Europe stabilize, regain a sense of vision, and remain a great source of welcoming cultural strength.