THE JUSTICE Department should be commended for taking action against alleged audacious economic espionage by China, targeting the United States. The indictments returned on Monday highlight in some detail what has been openly discussed for several years — that China, as a matter of state policy, uses computer hacking to steal secrets that benefit its companies, a heist that some have called history’s greatest theft of intellectual property. The indictments are a useful signal to China that this behavior is intolerable, but law enforcement can’t stop it. This is going to be a long battle, and it is going to be murky and uncertain.

Economic espionage is the theft of proprietary, industrial or company secrets for competitive advantage. The U.S. government carries out espionage for national security — and that encompasses a wide range of activity — but it does not grab information to benefit industry . The charges announced by Attorney General Eric H. Holder Jr. reflect a fundamental belief that theft on such a scale is wrong and criminal.

We should harbor no illusions that China shares these definitions or values. China is striving to leap several generations of economic growth in a relatively short period, and it sees national purpose in purloining valuable designs, plans, communications and all sorts of intelligence to advance that goal. Chinese enterprises are well known for making off with blueprints and know-how from Western joint-venture partners. No one should be shocked that China sent the military to scour the Internet for competitive advantage. In the past few years, Chinese cyberespionage has penetrated U.S. equity markets, defense contractors, insurance companies, museums, newspapers and much more. No amount of jawboning has done much to stop it.

The indictments may be one tool. Another would be to better secure the United States’ private sector, which remains vulnerable. Congress debated and ultimately failed to act on legislation that would have deployed U.S. government experts to help protect corporate networks. The idea of using the sophisticated tools of the National Security Agency may be no longer politically viable in light of the surveillance disclosures of late, but the corporate vulnerability remains.

A suspicion that all’s fair in cyberspace may have been enhanced by recent U.S. covert actions, such as the use of the Stuxnet worm to slow Iran’s enrichment of nuclear materials. So be it. The country can spare no effort at genuine national security online, whether in defense or offense. Even if adversaries don’t share U.S. values, they must know that those values and the United States’ vast trove of intellectual property will be defended. There should be more indictments of cyberespionage suspects. While prosecution may be difficult, at the very least these charges can expose the perpetrators and perhaps deter some of them in the future.