At 8:46 a.m. on September 11, 2001, the world changed, and so did the mission of the FBI.

September 11 was a milestone in the evolution of the Bureau. Years ago, the traditional image of the FBI was that we were “G-men” battling notorious criminals. Certain events crystallized this image in the mind of the public: the pursuit of Bonnie and Clyde, the Kansas City Massacre, and right here in Chicago, the John Dillinger shooting.

It was in Chicago that Dillinger graduated from bank robbery to murder, killing a Chicago police officer. And it was in Chicago, outside the Biograph Theater, that his crime spree and the FBI’s manhunt came to an end.

In the early 1930s, Dillinger and other gangsters were primarily planning bank robberies and jailbreaks. Contrast that with the terrorist planning we have seen in the past five years:

Three different plans. All of them complex, all of them potentially deadly. The threat landscape of the early 1930s seems simple by comparison.

Yesterday, we commemorated the fifth anniversary of the September 11th attacks. With this anniversary as a backdrop, today I want to talk to you about the FBI’s role in the struggle against terrorism—where we were, where we are now, and where we are heading.

Let us start with where we were five years ago today. The World Trade Center and the Pentagon were still smoldering. The FBI’s Evidence Response Teams were combing through the wreckage of Flight 93 in Shanksville. We were operating under the assumption—and the fear—that a second wave of attacks was imminent.

As we worked to put the puzzle pieces together, one thing became clear: Overnight, the stakes had risen dramatically. The scale of the terrorist threat had changed, and the FBI had to change with it.

On the morning of September 11, 2001, we faced two simultaneous challenges—responding to the immediate crisis and also preventing a future attack. After the planes hit, we knew we would have to chart a new course for the FBI. But first, we needed to provide immediate security.

And so within hours, the FBI mobilized to launch the largest criminal investigation in the Bureau’s history. We set up multiple command centers, including makeshift command posts in a garage on the West Side docks and on the deck of the USS Intrepid in New York. Virtually every agent and analyst across the country stopped what they were doing to run down leads related to the attacks.

As the investigation progressed, our next step was to establish a new mission and new priorities. Counterterrorism moved to the top. We then shifted resources and personnel to counterterrorism, but this could only carry us so far.

Looking ahead, we knew we would need more agents, more analysts and more translators. We would need better communication, better intelligence, and better information technology.

And so we began to build strategically, focusing on three main areas: intelligence, technology, and partnerships.

First, intelligence. The FBI has always excelled at collecting intelligence and using it to build cases and win convictions. But after the September 11 attacks we had to improve the way we analyzed and shared intelligence, and we had to use intelligence to drive our investigations, not the other way around.

We started by more than doubling the number of intelligence analysts. We established field intelligence groups in every FBI office. These groups combine the expertise of agents, analysts, translators, and surveillance specialists. We integrated our intelligence program with other agencies under the Director of National Intelligence.

Today, intelligence is woven into every FBI program and every FBI operation, from counterterrorism to counterintelligence to cyber. Intelligence played a critical role in disrupting those terrorist plots I mentioned earlier.

Second, technology. Before the September 11 attacks the FBI’s information technology was outmoded. In the past five years, we have installed thousands of state-of-the-art computers and secure global networks. We have developed sophisticated databases and search engines. And we are developing a fully automated, web-based case management system.

And third, partnerships. We now work side-by-side with the CIA and Department of Homeland Security at the new National Counterterrorism Center and other fusion centers around the country. We expanded our Joint Terrorism Task Forces, from 35 in 2001 to over 100 today. On these task forces, FBI agents and federal, state and local law enforcement work as a team to follow every counterterrorism lead.

We have also strengthened our relationships with our international law enforcement partners. The FBI now has offices in nearly 60 countries, where we are tightly integrated with our overseas counterparts. We train together. We work hand-in-hand on multinational task forces and investigations. The FBI has assisted counterterrorism investigations from Riyadh to Madrid and from Amman to London. For example, we worked very closely with British and Pakistani intelligence officials on the recent London plot to blow up planes headed for the United States.

I just covered five years of complex changes in a few minutes—but that barely skims the surface of the FBI’s transformation. As business and community leaders, I’m sure you can appreciate the thought, time, and planning that went into each decision.

I often compare transforming the Bureau with changing the tires on a car that is speeding down the highway. Yet we had to do more than just change the tires. We had to overhaul all our systems. And we made this transformation—while protecting America from terrorism and while continuing to combat traditional crime.

As a direct result of our labors, we have reached an important milestone. It has been five years without an organized attack in the United States. We should all be thankful for that.

For my part, I am particularly proud of the men and women of the FBI, and I am thankful for the hard work and friendship of all our partners, from the Chicago police to our military forces to our counterparts in other countries.

We did not reach this milestone by accident or by coincidence.

It is difficult to measure progress in counterterrorism. We cannot post a profit. We cannot quantify freedoms protected and lives saved. We cannot measure the absence of damage—other than saying, “None of our cities was attacked; none of our citizens was harmed; none of our security was penetrated today.”

Yet this is our definition of success. Over the past five years, we have made tangible progress in reaching that goal.

Working with our military and law enforcement partners throughout the world, we have weakened al Qaeda as it existed on September 11, 2001. We have captured or killed many al Qaeda leaders and operatives. By pulling out the threads of al Qaeda’s top leadership, we have seen the fabric of their organization begin to fray.

We have shattered their hierarchy and eliminated training camps. We have frozen their finances and disrupted their communications. We have uncovered their cells and prevented attacks.

It is one thing to say that we doubled the number of intelligence analysts and nearly tripled the number of Joint Terrorism Task Forces. These are just statistics—until you realize that it was our improved human intelligence that was the key to cracking the Toledo terrorist cell I mentioned earlier. It was our stronger partnerships with state and local police that were pivotal to disrupting the terrorist plot in Torrance, California.

It is good to reflect on how far we have come, but the recent cases in Canada and Britain remind us that we still have a long way to go. Terrorists have attacked other nations. Terrorists still want to attack us. They are not the type of people to pursue another line of work.

We have adapted, but so have our adversaries. We have severely restricted al Qaeda’s movements and momentum, but terrorists are finding other ways to communicate, to raise money, to recruit, to train and to plan attacks.

Instead of training camps, we have seen a rise in websites that promote violent jihad and give step-by-step instructions on how to build suicide vests and explosives. Instead of receiving funding from al Qaeda, terrorists are committing crimes to raise money for their operations. And instead of hand-picked teams who received training, funding, and direction from al Qaeda leaders, we have seen self-starting, self-radicalizing, self-financing cells spring up in our communities.

That these homegrown cells may not necessarily be al Qaeda does not diminish the threat. They may not even have a formal affiliation with al Qaeda, but they do embrace the same radical ideology. And they are just as willing to kill as the terrorists who attacked us on 9/11.

On top of all this, the recent London-based plot to blow up airplanes bound for the United States indicates that terrorists are still attempting large-scale, coordinated attacks. They are fractured, but they have not given up. They are trying to find new ways to use our freedoms against us.

The plots I mentioned earlier are concrete examples of attacks we have been able to prevent, but we can take little comfort from that. As British terrorism scholar Paul Wilkinson put it, “Fighting terrorism is like being a goalkeeper. You can make a hundred brilliant saves but the only shot people remember is the one that gets past you.” We have to expect that terrorists will continue to try to get past our defenses.

In the simplest terms, what makes the FBI different from one of your companies is that if you have a bad quarter, you can make it up during the next quarter. Not so for the FBI. The American people are our shareholders. The Congress is our Board of Directors. And human lives and national security are on the line every day.

The FBI—and America—cannot afford to become complacent just because we have been safe for five years. We must be more vigilant, not less. As we mark another anniversary, we must recommit ourselves to building a stronger FBI for the future.

Each year that passes in safety is an important milestone—but it is not the end of the mission. Each terrorist cell disrupted is a battle won—but it is not the end of the war.

The war on terrorism will not end in a single, decisive battle. It may persist for generations, and we may have setbacks along the way. It will demand more than technology and intelligence and organizational change. It will demand the continued resolve of the FBI and the American people.

This struggle will be hard fought, and hard won—but it will be won. In the meantime, we in the FBI will work with our partners to hold the threats at bay.

Each time you go to bed relieved that we passed another day without an attack, remember that across the world, FBI agents and analysts are working through the night to keep you safe.

Over nearly 100 years of history, the FBI has faced down many threats. It has protected citizens from organized crime. It has rescued children from the hands of kidnappers. It has safeguarded our national security from international spies. It has defended the civil rights and civil liberties of all Americans.

Our adversaries are still out there, and they are still dangerous, but they are scattered and we are united—with you, with the Chicago police, with our partners in law enforcement and intelligence across the world. Their desire to harm our citizens is no match for our desire to protect our citizens. Their determination to destroy our freedoms is no match for our determination to defend those very same freedoms.

Defending freedom is the history of the FBI. And it is also the future of the FBI. We will never give up, and together we will prevail.