Technically Russia as they're land would be less irradiated on average then the US's. This is only because Russia is much bigger then the US.
A recently published article from Aviation Week & Space Technology, based on the interview with a US Navy pilot, who participated in the planning of strikes against Iraqi air defense during the early stages of the operation Desert Storm, indicates that there is "nothing invisible in the radar frequency range below 2GHz" [reverse translation from Russian] and with a well-designed low-frequency radar it is possible to "see even a dragonfly at a great distance" [reverse translation from Russian].