Radio waves are a pretty big part of the EM spectrum. Do you mean like sudden intense jamming from outer space, or like physics just stops suddenly?

If its the former, its going to depend on what parts of the spectrum are being jammed, but most modern militaries are actually pretty prepared for radio jamming and have alternate systems for most critical applications. The scenario is fairly similar to the EMP saturated environment expected in a nuclear war. The military has spent a lot of time and money preparing to moderate the worst of those effects. Civilian systems would not handle things very well at all. Expect lots of catastrophic cascading failures and instances of permanent damage.

If its the later, all bets are off any time physics breaks.