Air Force officials have started planning a ten billion dollar modernization of the B-2 stealth bomber fleet to include a new receiver using VLF waveform technology that allows the bomber to receive messages in the event of a high altitude electromagnetic pulse, and outfitting the aircraft for next-generation digital nuclear weapons such as the B-61 Mod 12 with the new tail kit, and Long Range Stand-Off weapons- (air-launched nuclear cruise missiles).
From Military.com