USML Category XI(a)(3)(xxvii):

> (xxvii) Bi-static/multi-static radar that exploits greater than 125 kHz bandwidth and is lower than 2 GHz center frequency to passively detect or track using radio frequency (RF) transmissions (e.g., commercial radio, television stations);

There are separate ITAR provisions for radio direction finding, but these come with plenty of exclusions for systems not designed for defence applications or signals intelligence etc, and otherwise not meeting certain performance requirements, such as those in 5A001.e.