Especially when they're bombs:
In July, 2005, I asked a member of a Baghdad-based military bomb squad about the radio-frequency jammers his team was using to cut off signals to Iraq's remotely detonated explosives. His response: "I can't even begin to say the first fucking thing about 'em." A few days later, one of those jammers seemed to save me and him from getting blown up. Months after that, David Axe was thrown out of Iraq by the U.S. military, for a blog post which mentioned the Warlock family of jammers.
So I was more than a little surprised, when I saw that Wikileaks had posted a classified report, outlining how the Warlock Red and Warlock Green jammers work with — and interfere with — military communications systems. The report, dated 2004, gives specific information about how the jammers function, their radiated power and which frequencies they stop. That Baghdad bomb tech would've put his fist through a wall, if he saw it out in public.