On March 1, the Department of Homeland Security celebrated its fifth-year anniversary. For many of us, it is hard to believe more than five years have passed since Congress enacted the Homeland Security Act, bringing together more than 30 federal offices and agencies to set about the urgent task of protecting the American people from all hazards, including acts of terrorism.

Of course, five years isn’t a lot of time in the lifespan of a Cabinet-level department. Nevertheless, we have made striking progress to build a set of critical national capabilities that in many cases did not exist prior to 9/11 but because of our efforts exist today.

For example, prior to 9/11, we did not have an effective system for identifying dangerous people arriving at our nation’s ports of entry. This is no longer the case. Today we capture the fingerprints of millions of international visitors each year, confirm their identities within seconds, and check their biometrics against integrated watch lists in real time. This has created a formidable barrier against the entry of known and unknown terrorists while improving the travel experience for everyone else.

Prior to 9/11, we did not have a sound strategy for securing our borders or enforcing immigration laws. That too has changed. To protect the border, we have built hundreds of miles of fence, deployed new technology, and are on track to double the size of the Border Patrol by the end of this year. We also have deported hundreds of thousands of fugitives, criminals, and illegal alien gang members. As a result, apprehensions are down, worksite enforcement is up, and momentum is shifting in our favor.

Prior to 9/11, we did not scan cargo for radioactive materials at our nation’s seaports. Today, we scan virtually 100 percent of arriving cargo, we require advance information on all shipments bound for the United States, and we have deployed officers overseas to inspect cargo before it leaves the foreign port.

Prior to 9/11, we did not have a robust aviation security system to safeguard the 2 million domestic air travelers who fly every day. Today, more than 20 layers of security are in place — from hardened cockpit doors to federal air marshals to 100 percent screening of passengers and their bags.

Prior to 9/11, we did not have national chemical security standards. Today, with authority from Congress, we have implemented tough chemical security standards to protect chemical facilities and chemicals in transit. We also have worked with the private sector to develop security plans for our nation’s 17 critical infrastructure sectors.

And prior to 9/11, we did not have an effective emergency preparedness and response system. By integrating lessons from Hurricane Katrina and other disasters, we have rebuilt the Federal Emergency Management Agency, giving it capabilities it has lacked for decades. We released a new National Response Framework to further unify federal, state, and local emergency response. And we have engaged the American people as never before in a nationwide effort to build a culture of preparedness for individuals, communities, and businesses.

As we look ahead to the next five years, we must press ahead in four critical areas. First, we must sustain our progress at the border by deploying additional fencing, Border Patrol, and technology. In addition, Congress must pass a long-term immigration solution. Unless that occurs, our nation’s immigration problems will only get worse and the American people will only grow more cynical about their government.

Second, we must finish the job of developing secure forms of identification to prevent terrorists, criminals, and illegal aliens from using fraudulent identification to elude authorities or engage in illegal activity. Efforts such as REAL ID and new travel document requirements at the border will help reduce the ability of terrorists and criminals to perpetrate identity theft or move freely within our country.

Third, we must strengthen our cyber defenses in partnership with the private sector to protect against a large scale cyber attack. Cyber attacks are on the rise. We must accelerate our efforts to prevent their occurrence and mitigate their impact.

Finally, we must continue to institutionalize the department’s essential functions. Among other things, this means encouraging Congress to streamline its oversight and refrain from making constant readjustments to the department’s organizational structure. Turf battles, competing direction, and constant reorganizations make our difficult job even harder.

The department has come a long way in its first five years. The next five years will surely bring additional challenges. Fortunately, we have laid a strong foundation for our future security and established the necessary partnerships to ensure our future success. We appreciate the support of Congress, our public and private sector partners, and the American people as we build on our progress and continue to keep our nation safe in years to come.

Chertoff is secretary of the Department of Homeland Security.