The last time there was a terrorist attack on America, we got the Department of Homeland Security and the Transportation Security Administration.

Each entity has spent billions to keep us safe, but neither could stop two brothers, Tamerlan, a permanent resident, and Dzhokhar Tsarnaev, a newly minted U.S. citizen, who lived in America and, reportedly, became radicalized jihadists, from killing and maiming innocent people at the Boston Marathon last week.

According to Dana Priest and William M. Arkin of The Washington Post, “Some 1,271 government organizations and 1,931 private companies work on programs related to counterterrorism, homeland security and intelligence in about 10,000 locations across the United States. ... An estimated 854,000 people, nearly 1.5 times as many people as live in Washington, D.C., hold top-secret security clearances. ... In Washington and the surrounding area, 33 building complexes for top-secret intelligence work are under construction or have been built since September 2001. Together they occupy the equivalent of almost three Pentagons or 22 U.S. Capitol buildings — about 17 million square feet of space.”

All of that failed to prevent the Boston bombings. The massive manpower, sophisticated equipment and money could not stop the Tsarnaevs from constructing improvised explosive devices (IEDs), including “pressure cooker” bombs.

Despite a domestic army of federal, state and local forces, the suspects managed to evade capture for days until Tamerlan was killed in a shootout and David Henneberry, a Watertown resident, found Dzhokhar hiding in his boat in his backyard. Henneberry called 911 and the wounded suspect was taken into custody.

The media have reported on the backgrounds of the two men. The FBI interviewed the older brother, 26-year-old Tamerlan, at the request of a foreign government, probably Russia, which expressed concern about his ties to Chechen extremists. The FBI, reportedly, could do nothing about Tamerlan under current U.S. law because there was no direct evidence of a terrorist plot.

How much confidence should Americans have in their government for keeping us safe when two young men can wreak havoc, shutting down a major city?

One thing the U.S. government should decide is whether or not to allow people into America from countries where radical Islam and “jihad” are taught. The hope has been that letting them live here would lead them to become more like us, more accepting of our way of life.

In fact, their stay in America seems to have reinforced a radical brand of religion and its worldview that are intended to destroy countries like America whose freedoms and “libertinism” they despise.

The UK Daily Mirror reported Sunday that the FBI was hunting a 12-member “sleeper cell” they say is linked to the Tsarnaev brothers. Quoting a source close to the investigation, the Mirror reported, “We have no doubt the brothers were not acting alone. The devices used to detonate the two bombs were highly sophisticated and not the kind of thing people learn from Google.”

More must also be done to curtail the admission of radical imams and the construction of mosques and Islamic schools where hatred of America, Jews and Christians is preached and taught.

How many sleeper cells are there in America? They must be found and dismantled. As offensive as this may be to some sensibilities, it is either that, or the offense of more terrorist attacks by people who hate us and are willing to die in the pursuit of goals they believe are dictated by their god.

How many more Americans must be killed and wounded before we fight back, not just overseas, but here? Our enemies are fighting us here. It’s our country, not theirs. We must fight for it.

Osama bin Laden’s announced intention was to conduct a “war of a thousand cuts” against America to harm our economy and permanently change our way of life. If he can see from Hell, he must be pleased about the way things are going.

[Cal Thomas is America’s most widely syndicated op-ed columnist, appearing in more than 600 national newspapers. He is the author of more than 10 books and is a FOX News political contributor since 1997. Email Cal Thomas at [email protected].] ©2013 TRIBUNE MEDIA SERVICES, INC.