Well, that's one of the tin-foil hat stories about HAARP. The most persistent is that it's actually a weather control program, based on Nikolai Tesla's work. The site linked elsewhere as a reply to you maintains that HAARP is a research project on the ionosphere. I also heard that it was actually part of the ELF (extreme low frequency) system for broadcasting messages to submerged subs.
NASA flew a penetrating radar system on the shuttle some years ago that was able to detect long buried canals, roads and even villages. According to Tom Clancy (as well as other sources) this mission wasn't about archaeology, it was meant to demonstrate our capability to pick out hidden hardened sites, therefore making Soviet attempts to build hidden missle silos moot and thus encouraging them to negotiate at the START talks. They have continued to fly the radar, as well as one adapted to an airplane (see http://www.sciencedaily.com/releases/1998/02/980216073822.htm for an article about archaelogical discoveries at Angkor Wat).
I still have this funny feeling that we know where the WMD are buried and we're holding off for our own reasons. Part of it may be giving the dims and the European appeasers enough rope to hang themselves. We may also be watching the sites to see who goes there. I can only hope.