When Khalid Mohammed confessed to plotting as many as 31 different attacks on high-profile targets in the United States and throughout the world last month, it was a chilling reminder that our nation is still at war with an evil enemy. But his words revealed something even more significant—al Qaeda’s diminished capability to launch attacks on our homeland.

In fact, al Qaeda’s success rate in the United States since 9/11 is zero — thanks in part to a series of comprehensive security measures that have strengthened our ability to stop the enemy.

These new tools are aimed at preventing attacks before they occur by gathering intelligence through surveillance, interrogation, and other lawful means. And they work. Since September 11th, 150 terrorist threats and cells have been disrupted, 3,000 operatives worldwide have been incapacitated, and nearly two-thirds of al Qaeda’s senior leaders have been captured or killed.

Congress is constantly evaluating these measures to ensure they protect our civil liberties and also secure our safety. Of course, that hasn’t stopped congressional Democrats from attacking them—even threatening to undo the progress despite the fact that our security depends on the continuation of these initiatives.

Terrorist Surveillance

When the New York Times revealed the existence of this confidential program, Democrats quickly branded it warrantless domestic eavesdropping. In fact, the program allowed law enforcement to monitor calls and emails of suspected al Qaeda terrorists only when one party was located outside the United States. CIA Director Michael Hayden confirmed the value of the program by revealing that it helped prevent an attack on the Brooklyn Bridge and would have “detected some of the 9/11 al Qaeda operatives in the United States.”

Regardless, more than 90 percent of House Democrats voted against legislation that would have made it easier to monitor terrorist communications. Some went so far as to call the program criminal and threaten impeachment.

I hold great respect for the Fourth Amendment, but I also value the lives of the American people, and I understand that the terrorists’ war against us sometimes requires gathering intelligence quickly to stop a new attack from occurring. For this very reason, the Supreme Court has ruled that the president has the right to conduct warrantless searches when “special needs” exist. In January, the attorney general won approval of new rules to obtain warrants without compromising the “speed and agility” that made this program so successful in tracking terrorists.

Patriot Act

The Patriot Act brought intelligence-gathering and information-sharing into the 21st century by updating an array of laws. Its most significant achievement was tearing down the wall that prohibited the law enforcement, intelligence and defense communities from sharing information—a top recommendation of the 9/11 Commission.

Unfortunately, the law came under political attack soon after its enactment—despite winning approval with overwhelming bipartisan support just weeks after 9/11. For instance, a 2003 bill by Democratic Presidential candidate Dennis Kucinich that attracted 29 cosponsors would have repealed major provisions of the law, including wiretaps, record searches and the detention and deportation of non-citizens.

The law itself nearly expired last year when 77% of Democrats in the House voted against its reauthorization and a filibuster was threatened in the Senate. Look for possible changes to the Act this year as Congress continues moving forward with new rounds of hearings.

Interrogation of Enemy Combatants

The lawful interrogation of terrorists has yielded a treasure trove of information, including the identities of operatives, locations of cells, and details of plots. But that didn’t stop 82 percent of Democrats in the House and 73 percent of Democrats in the Senate from voting against legislation creating a new system for interrogating and prosecuting terrorism suspects.

That legislation, which guarantees detainees the right to counsel, the right to cross-examine witnesses, and even the right to appeal a conviction to the Supreme Court, replaced an earlier version of military tribunals that were deemed unconstitutional.

The new system produced its first guilty plea late last month when Australian David Hicks, an al Qaeda operative who trained with the terror group, supported the Taliban and conducted surveillance against the United States, admitted to providing material support for terrorism.

In recent days, Democrats have reiterated their pledged to push legislation to expand rights for the roughly 80 other terrorists, including several self-described jihadists, who face prosecution under the new system.

The opponents of these critical national security measures never seem at a loss for words, yet they often avoid answering the most fundamental question: What might have happened if they were not in place?

Khalid Mohammed’s confession provides a likely answer.

—The Honorable Vito Fossella represents Staten Island and parts of Brooklyn.