Some call cyberspace the new domain of war, after land, sea, air and space. The 2010 Stuxnet cyberattack on Iran's uranium enrichment plant, suspected to have come from Israel or the US, seemed to confirm this status.

The U.S. has built, flown, pointed and triggered a missile designed specifically to carry a directed-energy weapon. That payload, expected to be operational soon, will be able to disrupt, shut down, spoof or damage electrical systems, but little has been revealed about the project.

Computer security researchers are warning that a new version of the sophisticated cyberweapon that sabotaged Iran’s nuclear program could be the precursor to a new wave of cyberattacks.

Top Pentagon officials considered using their secretive arsenal of cyberweapons to disrupt Libya’s air defenses before deciding that bombs would be the better option for preparing the way for U.S.-led coalition airstrikes.

New legislation, passed June 9 by the U.S. House of Representatives and referred to the Senate's Energy and Natural Resources committee, hopes to strengthen the electrical grid’s robustness against attacks from solar flares or terrorists among other threats.

While the British government said this week that it is developing cyber-weapons to respond to debilitating attacks on critical national infrastructure, such as the electricity grid, the Pentagon says it may use traditional "kinetic" hardware to respond to such incursions.

The U.S. is vulnerable to a cyber attack, with its electrical grids, pipelines, chemical plants and other infrastructure designed without security in mind. Some say not enough is being done to protect the country.

A recent cyber attack on Iran's nuclear program could have triggered a disaster comparable to the one in Chernobyl 25 years ago, Russia's envoy to NATO said.

Epitaphs for the Mubarak government all note that the mobilizing power of the Internet was one of the Egyptian opposition’s most potent weapons. But quickly lost in the swirl of revolution was the government’s ferocious counterattack, a dark achievement that many had thought impossible in the age of global connectedness. In a span of minutes just after midnight on Jan. 28, a technologically advanced, densely wired country with more than 20 million people online was essentially severed from the global Internet.

The U.S. military has no shortage of devices — many of them classified — that could restore connectivity to a restive populace cut off from the outside world by its rulers. It’s an attractive option for policymakers who want an option for future Egypts, between doing nothing and sending in the Marines. And it might give teeth to the Obama administration’s demand that foreign governments consider internet access an inviolable human right.