In the skies above Libya, the U.S. Navy has been deploying a small fleet of supersonic EA-18 Growler jets to “jam” Moammar Kadafi’s ground radar, giving NATO fighters and bombers free rein to strike tanks, communication depots and other strategic targets.

It’s the latest demonstration of “electronic attack” hardware — the “EA” in the Growler’s name. Armies have been waging electronic warfare since World War II, but today’s technology packs a strategic wallop unforeseen even a decade ago.

With foreign adversaries continuing to improve their radar capabilities and air defense networks, and terrorists worldwide using modern consumer electronics to trigger explosives, the United States is spending billions of dollars in a massive effort to respond. These jammers, for instance, spew radio waves and emit other electromagnetic noise to jumble enemy electronic signals.

“War fighters have gone from using physical weapons like spears and knives, to chemical weapons such as gunpowder and explosives, to electronics with radio waves and computer codes,” said Peter W. Singer, a senior fellow at the Brookings Institution. “It’s a natural evolution in warfare.”

At a time when the defense budget is being eyed for cuts, electronic attack technology is one of the few areas — along with drones and cyber security — in which President Obama wants to boost spending.

The Pentagon is seeking to increase its technology research budget, which includes electronic warfare, to $12.2 billion in fiscal 2012 from $11.8 billion — and that doesn’t include spending in the classified portion of the budget.

Critics cite this type of military spending as another example of bloat in the $729-billion defense budget.

“Of course there will be priorities, but the government has to ask themselves at some point: ‘Do we really need this?’ ” said Laura Peterson, a national security analyst for Taxpayers for Common Sense, a government watchdog group. “We haven’t seen the kind of discipline that’s needed to really rein back the defense budget.”

The Pentagon has also requested $1.1 billion for 12 more Growlers, even as defense contractors are vying for lucrative rights to build the next generation of jamming devices, which would vastly expand the military’s ability to disrupt and deceive enemy electronics.

But defenders of jamming technology say it is cost effective because it prevents planes from the U.S. and North Atlantic Treaty Organization from getting shot down.

“An increase in funding is needed to maintain the edge in electronic warfare,” said Loren Thompson, defense policy analyst for the Lexington Institute in Arlington, Va. “Other nations have drastically improved their electronics systems and gotten better defending against electronic attacks.”

Electronic warfare technology — much of it top secret — aims to counterbalance foreign militaries’ multimillion-dollar investments in shoring up air defenses and continuing advancements in radar detection.

With a price tag of about $74 million each, Boeing Co.'s Growler is a showpiece of American electronic know-how with high-powered radar systems made by Raytheon Co., and tactical radar jammers made by ITT Electronic Systems and Northrop Grumman Corp.

The Growlers, based at the Naval Air Station Whidbey Island in Washington, look like imposing fighters armed to the hilt with big bombs slung under their wings ready to drop on the enemy. That’s because the plane is a modified version of the F/A-18 Super Hornet. But a closer look reveals that instead of bombs, it carries an array of radars, antennas and high-tech gear.

Each of the devices hanging from the Growler’s wings performs a different function, including pinpointing the location of enemy radar sites, intercepting and jamming radio signals and following the changing enemy radar tactics.

“Our job is to control the electromagnetic spectrum over the battlefield,” said Capt. Mark W. Darrah, Growler program manager for the Navy. “The only way you know if an electronic attack was successful is if every plane returns safely from their missions.”

The proof of its success in Libya, he said, is that NATO has carried out 5,000 strike missions and no aircraft has been shot down.

The Growlers’ fuselage sections are manufactured inside Northrop’s 1-million-square-foot facility on Aviation Boulevard, about a mile south of Los Angeles International Airport.

Until the Growler was deployed in Libya, the Navy was still operating the Vietnam-era EA-6 Prowler for electronic attack missions. The Growler is nearly twice as fast as its predecessor, traveling at speeds of up to 1,100 mph, and takes two rather than four people in the cockpit to carry out missions.

But as the Growler enters wartime service, work has already begun on a new jamming device for the jet to give it an even greater ability to befuddle the enemy.

Four aerospace giants are competing for a jamming device contract estimated at $2 billion: Northrop, BAE Systems, and Raytheon Co and a team of ITT and Boeing. A total of $168 million has been handed out by the Navy to the companies for research and development on the program.

The goal is to begin producing new jamming devices on the Growler, the upcoming F-35 Joint Strike Fighter jet and possibly unmanned drones by 2018, said defense analyst Thompson.

Requirements for the new jammer haven’t been finalized or announced. Little is known about the details and capabilities as electronic warfare has always been shrouded in secrecy in order to stay ahead of potential adversaries.

But that hasn’t stopped speculation about what’s being considered and how it might be used. It is likely to give the Growler the capability to launch cyber attacks by slipping viruses into enemy computer networks from thousands of feet above, Thompson said.

This technology may have been used by Israel in a 2007 bombing of a Syrian nuclear facility, according to counter-terrorism expert Richard A. Clarke, a former advisor to the National Security Council, in his 2010 book, “Cyber War.”

He wrote that during the attack, Israel may have used radio waves to transmit computer data packets the Syrian air defense network.

“Those packets made the system malfunction, but they also told it not to act [like] there was anything wrong with it. They may have just replayed a do-loop of the sky as it was before the attack,” Clarke wrote. “The sky would look just like it had when it was empty, even though it was, in actuality, filled with Israeli fighters.”

Another weapon under development in the nation’s electronic arsenal is a 9-foot-long missile armed not with explosives but with a warhead that spews electromagnetic waves to disable and distract enemy defenses.

Work on the warheads is being done at Raytheon’s sprawling electronics facility in El Segundo. Engineers there have been perfecting the electronic attack technology in underground clean rooms for decades.

Details of the miniature air-launched decoy, or MALD, emerged recently at the Paris Air Show, where Raytheon announced the first successful test of the technology. The Pentagon has invested more than $500 million in the technology, which is being developed for the Air Force.

The missile weighs less than 300 pounds and could be carried by F-16 and F/A-18 fighters or B-52 bombers. Or they could be dropped by the dozens from massive cargo jets. Although small, the MALD’s high-tech electronics make them appear to be as large as a fleet of bombers on enemy radar screens.

“This is the new generation of electronic warfare,” said Jeff White, a Raytheon business development manager and former Marine Corps pilot. “The enemy should never know what’s coming their way.”