It is more IR than radar. Any kind of firearm, from a pistol up, produces a bright IR flash.
Nothing can be done to conceal this IR flash. I believe that the US forces in Iraq ARE ALREADY using IR technology to return fire. As soon as somebody opens up, fire is returned. Sometimes, it it not quick enough. However, the Iraq terrorists are beginning to learn just what you said. To fire at an American force is to commit suicide. That message is coming across.
David F Mayer