The last Tuesday, September 11, dawned bright on American businesses. Of course, there were problems, including a weak economy and a falling stock market. Those problems are still with us, but how times have changed.

It used to be that businesses relied primarily on our government to deal with national security and external threats. On the last Tuesday, September 11, foreign terrorists bypassed the government and attacked individuals and American businesses using the facilities of American businesses.

Today, terrorists and criminals continue to bypass governmental security measures and to attack individuals and American businesses by using American business facilities. The launch pads for attacks are the telecommunications networks of major American companies and the online services of American businesses.

Recently, several reports have alleged that the People’s Liberation Army of China broke into a Pentagon computer network. The relevant point is not whether the Pentagon network was breached (the Pentagon will not confirm it) or whether China is the infiltrator (China denies wrongdoing, and anyone clever enough to infiltrate the Pentagon security system is probably clever enough to disguise his or her identity). Rather, the poignant result is that if the Pentagon, with all of its resources devoted to security, has computer networks that are less than fully secure, how secure can an individual’s or a private company’s computer system be?

The answer is obvious. Unfortunately, cyber attacks are the norm rather than the exception. Criminals around the world seek to infiltrate, survey, alter, and disable computer networks owned by government agencies, private corporations, and even the domain name registries that direct traffic on the Internet itself. Robot networks, or “botnets,” infect the computers of millions of unsuspecting Americans. Cyber attacks happen every second of every day, and most of us are oblivious.

Even before 2001, American businesses spent billions of dollars on software, hardware, physical premises security, and personnel to protect their internal networks and computers from spam, viruses, and other harmful attacks. But since 2001, private spending on security has accelerated both because of the increased perceptions of risk and because our government is hamstrung from doing much to protect us.

Cyber criminals do not break and enter the Pentagon or a private company through a basement window. Rather, they enter through computer systems that are connected to public telecommunications networks, of which there are hundreds of independently owned networks in America alone. The deadly venom of Al Qaeda and Osama bin Laden reaches the world primarily not through car bombs but through videos on the Internet.

Cyber criminals do not don military uniforms, nor do they seek court permission before conducting attacks. They do not abide by the USA Patriot Act before surveying the American public or before infiltrating government networks. Cyber criminals do not notify telecommunications companies that they want access to sensitive records; they simply take information as they choose, largely undetected.

The Patriot Act gives law enforcement and national security agencies broad powers to collect information. Cyber criminals attack America with enormous technological capabilities; it only seems just that our government can fight back with its own technological weapons.

But while the rules of conventional warfare are largely symmetric, the legal rules of cyber warfare are not. Villains infiltrate and steal at leisure; law-abiding citizens and companies defend themselves as best they can; and the government tries to find constitutional means to fight those who would destroy it. Last week, a federal district judge in New York, Victor Marrero, ruled unconstitutional various provisions to the Patriot Act that require parties — primarily telecommunications companies — both to comply with FBI information requests and to remain silent about those requests without judicial review. It is the lack of judicial review that troubles Judge Marrero.

In the war on terror, American businesses are all too often the witting accomplices of the federal government in tracking down terrorists and the unwitting accomplices of terrorists in surveying and attacking both America and the businesses themselves. Public attention often focuses more on the consequences of the former than the latter.

Today is Tuesday, September 11. We are still under attack.

A former FCC commissioner, Mr. Furchtgott-Roth is president of Furchtgott-Roth Economic Enterprises. He can be reached at hfr@furchtgott-roth.com.