The virus had appeared there in an earlier incarnation and exported information on troop movements. The story quotes unnamed authorities who believe it came from China, though it’s not clear whether it was that government’s doing or the work of private hackers.

According to the Los Angeles Times, however, Russian hackers could be involved. It says a massive malware attack hit hard within the U.S. Central Command, which oversees U.S. involvement in Iraq and Afghanistan,  and it penetrated at least one highly protected classified network. It reports senior military leaders thought the incursion serious enough that they decided to brief the president about it.

Though the military is continually the target of hackers, the Times quotes one unnamed defense official saying:

This one was significant; this one got our attention.

A couple of weeks ago the military banned use of USB drives in an effort to stem the spread of viruses.