By: William Inboden

The Islamic State group’s terrorist assault on Brussels was a shock but not a surprise. Since last November’s attacks in Paris, American and European counterterrorism officials knew that ISIS members and sympathizers in Paris, Brussels, and other European cities were plotting further violence. But despite the courage and devotion of countless European intelligence and law enforcement professionals, the European counterterrorism system was overwhelmed by too many would-be jihadists to track, too many potential plots to monitor, and too many civilian targets to protect. The attack highlights an uncomfortable truth: The American and European approach to combatting ISIS is not succeeding. It is time for our nation’s leaders and Europe’s leaders to adopt a new offensive strategy.

Our current strategy is largely defensive, consisting of massive surveillance efforts to detect and disrupt plots in the United States and Europe, and a narrowly tailored military campaign in Iraq of limited bombing runs and a small number of special operations forces under tight restrictions.

A new strategy would recognize that ISIS is a global threat that has now directed or inspired terrorist attacks on five continents. The terrorist group is unique among jihadist groups. Its leaders control large swaths of territory in Iraq, Syria, and Libya, and they have self-sustaining revenue streams from taxes, oil smuggling, extortion, and ransom payments. They have thousands of fighters who hold Western passports. They possess and use chemical weapons and are able to attract recruits worldwide through the creation of a social media network unparalleled in the history of warfare.

On top of this toxic combination, they have the capability and declared intention of further striking Europe and the United States.

What would an American-led offensive strategy against ISIS entail?

It means recognizing the need to destroy the group’s core strength: its establishment of a caliphate and its territorial control in Iraq, Syria, and Libya. The caliphate is the source of both its hard and soft power. It provides safe haven and training camps for its forces and its source of revenue. It also demonstrates power and legitimacy that attracts other would-be jihadists.

Specifically, a new strategy would entail a significantly escalated military campaign, including a substantial increase in special operations forces and joint tactical air controllers on the ground to better identify bombing targets, kill, or capture fighters, and help train and embolden local forces such as the Kurds, Iraqi army, and others.

We also need to increase the effectiveness and lethality of our bombing campaign with loosened rules of engagement. Recent reports indicate that up to 75 percent of American bombing sorties return to base without having dropped any ordnance because of limited target options and overly restrictive rules.

In Syria, we need to create a safe haven and no-fly zone to protect Syrian refugees and reinforce the beleaguered moderate Syrian rebels. Increasing the arms we provide to the Syrian rebels and Kurdish forces is long overdue. Such American steps of leadership will also encourage our European and Arab allies to dramatically step up their commitment to the fight, including ground forces and increased bombing campaigns.

An offensive strategy against ISIS also means reinvigorated diplomacy in the region. The U.S. needs to repair our badly bruised relationships with our Arab allies such as Iraq, Saudi Arabia, Jordan, the United Arab Emirates, and Egypt. They mistrust us because of our perceived tilt toward Iran and our perceived disengagement from the region. Restoring these diplomatic ties will elicit more allied cooperation and military force contributions.

Finally, winning the war against ISIS means winning the battle of ideas against jihadist ideology. For every fighter we kill or capture, more are being created through the radicalization process driven by social media. Our best allies in this struggle are peaceful Muslims who reject violent jihadism. We need to support them in their efforts to delegitimize jihadist ideology and curtail recruitment of new jihadists.

The war against ISIS is reminiscent of the Cold War—a generations-long conflict that spanned the globe—and includes military, economic, diplomatic, and ideological dimensions. Through strength, wisdom, resolve, and patience, the free world eventually prevailed against Soviet communism.

It can do so again in this twenty-first century war against militant jihadism. Doing so begins with a better strategy.

William Inboden is associate professor at the LBJ School of Public Affairs and executive director of the Clements Center for History, Strategy, and Statecraft at the University of Texas-Austin.

This piece originally appeared in the Dallas Morning News on March 23, 2016. It was later republished on June 27, 2016 for the Religious Freedom Project at Georgetown’s Berkley Center for Religion, Peace, and World Affairs.