WASHINGTON — Pentagon brass are increasing spending on electronic warfare systems because U.S. foes — big and small — are developing and using asymmetric tools, according to officials and documents.

“Big drivers” of the new focus include the need to jam triggering signals for improvised explosive devices in Iraq and Afghanistan, as well as emerging electronic threats posed by “large nations that have big defense budgets,” said Army Col. Laurie Moe Buckhout, chief of the service’s Electronic Warfare (EW) Division.

“The QDR is really broadening the focus and saying we need to be ready for a very broad array of enemies,” Buckhout said Feb. 11. “And what we’re seeing is all enemies are turning to asymmetric means of warfare — and EW, by its very nature, certainly goes down that path.”

The 2010 Quadrennial Defense Review says Pentagon officials see a “need to expand [U.S.] electronic warfare capabilities and enhance intelligence and information operations capabilities.” It puts EW tools in a group of urgently needed gear that includes “rotary-wing aircraft, unmanned aircraft systems, intelligence analysis and foreign language expertise, and tactical communications networks for ongoing operations, as well as more robust space-based assets.”

To that end, the 2011 budget request will add to the hundreds of millions of dollars spent annually to develop and buy EW tools, with more to come in future years, analysts and budget documents say.

Pentagon officials last spring and summer began discussing electronic warfare more often in public comments and congressional testimony. Around the same time, they launched several analyses of current and emerging EW threats, including one by Zachary Lemnios, the Pentagon’s director of defense research and engineering.

The Defense Department is increasing funding and focus on EW in large part because officials have concluded “any country having the internal capability to produce advanced electronics devices thus can produce advanced EW capabilities,” one Pentagon official said. “Since these capabilities are also marketed globally, they thus become available to all potential future adversaries of the U.S.”