In a multi-faceted offensive against the Islamic State terror group, the U.S. is striking in the cyber domain, according to the Pentagon's second-in-command.

"We are dropping cyber bombs. We have never done that before," Deputy Defense Secretary Robert Work told reporters traveling with him on April 12, according to CNN. "Just like we have an air campaign, I want to have a cyber campaign. I want to use all the space capabilities I have."

The cyber-bombing is part of a much larger battle against ISIS, but is it also a preemptive strike? On April 5, Adm. Mike Rogers, commander of U.S. Cyber Command, told Congress that one of his top concerns is the terror group gaining cyber warfare capabilities.

"The challenge I look for or that concerns me when I look at the future is what happens if the non-state actor – [ISIS] being one example – starts to view cyber as a weapon system? That would really be a troubling development," Rogers said, noting that ISIS already is adept in using the Internet for propaganda, recruiting, communications and coordinating activities.

Rogers cited other pressing concerns among his top priorities – specifically, Russia, China, Iran and North Korea – but ISIS and similar non-state actors have him worried as much as any of the other, bigger potential foes.

"I have not seen groups yet make huge investments in [cyber weapons], but I worry that it's a matter of time because it wouldn't take long," he said. "One of the challenges of cyber—and in addition we previously talked today about how it doesn't recognize boundaries—it doesn't take billions of dollars of investment, it doesn't take decades of time, and it doesn't take a dedicated workforce of tens of thousands of people like you see most nation states deal with."

Earlier this year, Defense Secretary Ash Carter issued CYBERCOM with orders to engage ISIS in cyberspace, he said at a Washington event the same day as Rogers' hearing. Previously he also publicly called for attacking via cyberspace the command and control functions of ISIS.

"I have given Cyber Command in the counter-[ISIS] fight really its first wartime assignment. And we're seeing how that works out," Carter said at the Center for Strategic and International Studies. "It means interrupting their ability to command and control their forces, interrupting their ability to plot, including against us here, and anywhere else against our friends and allies around the world. Interrupting their finances, their ability to pay people, their ability to dominate the population on whose territories they have tried to establish this nasty ideology."

Work put a slightly less-fine point on it in his comments to reporters.

"Right now it sucks to be ISIL," he said, using the acronym preferred by the military.