America cannot be safe from terrorism unless it roots out and destroys the Islamic State—at home and in the Middle East.

Recent attacks in Brussels, the December massacre in San Bernardino, and 32 other IS sponsored assaults in 24 cities around the world should drive home to Americans that no one on this planet is safe from radical Islam.

The founding principles of American civilization—the efficacy of democracy to guarantee personal security and the inviolability of human rights—are under attack and exploited by the IS.

Bombings in the Brussels airport and subway owe much to a democratically elected government’s failure to use its security apparatus to map and roll up the IS extremist network in Muslim districts of the city—despite repeated warnings the infestation was spreading and posed a lethal threat.

Now citizens of Belgium live in fear and are unable to move freely on their own streets.

Americans turn a blind eye too—obsessed with naïve notions about freedom of religion. And if we don’t become more realistic, we can look forward to more San Bernardino and perhaps 9-11 attacks.

Islamic radicalization spreads among young Muslims much as Christianity did during the Roman persecution, but with terribly evil intentions.

Young people, burdened by poverty and unemployment—and disaffected by the failed promises of politicians to create decent opportunities—are exposed to a poisonous religion of hatred toward Christians and Western Civilization.

Founded on mutated and twisted notions of Islam, this creed spreads through loosely connected networks of underground mosques and terrorist cells, by word of mouth and on the internet.

Police efforts to monitor those activities were frustrated in Brussels—much as they were in San Bernardino—in part, by religious leaders, friends, and families who turned a blind eye to terrorist preparations, refused to cooperate with authorities, and often shared some sympathy for those who hold western values and institutions in contempt.

Seen in this context, Islam and the Islamic community cannot be viewed as just another religion protected by the First Amendment.

Just as freedom of speech does not give individuals the right to scream fire in a movie theater, freedom of religion does not protect a community from conspiring—through direct actions by its more brazen members or estoppel by ignoring bomb building in neighbors’ basements.

Either the Imams, Islamic community leaders, and ordinary citizens earnestly assist authorities to root out the cancer in their midst, or western governments should subject Mosques and community groups to police surveillance normally reserved for movements dedicated to overthrowing governments and subjugating citizens—because those are the avowed intents of the IS.

As importantly, the Islamic State in Syria and Iraq provides essential support for the global terrorist movement and if not absolutely crushed, then its sinister designs to paralyze and destabilize western societies will in some places succeed.

Belgium is already skating on the edge of state entropy.

Europeans appear not to have the stomach to defend their own liberties. The Germans and others cried but refused to protect the Ukraine from Russian aggression and indicate no stomach for an expeditionary force to destroy ISIS on the ground.

Allied bombing of ISIS and technical and materiel support for the government of Iraq and anti-ISIS insurgents are proving simply not enough.

Despite repeated terrorist attacks, Europeans continue to believe tight security and good police work may somehow root out terrorists before they attack airports, subway systems, and stadiums filled with spectators.

That leaves America with stark and discomforting choices about having to go it alone—or with only limited European support—to destroy IS.

We are foolish to think, as the Europeans do, that we can continue to avoid the necessity of cracking down on radicalism in America or sending a ground force to the Middle East to destroy the IS homeland and liquidate its army.

Peter Morici is an economist and business professor at the University of Maryland, and a national columnist. He tweets @pmorici1.