Several variants of the A-12 and SR-71 were developed that could have provided the basis for interesting air to ground platforms. The M-21 was a variant of the A-12 designed to launch the D-21 autonomous drone. The D-21 could fly up to Mach 3.35 at 90,000 feet with a range of 3,000 nautical miles. It could carry a 425 pound payload and featured a very low radar cross section. An option with more possibilities would be the F-12, a variant of the SR-71 intended for use as an interceptor. One of cargo bays on the SR-71 was filled with missile guidance system equipment, while the other was equipped with three AIM-46 Falcon missiles. The AIM-46 later provided the airframe for the AGM-76 Falcon ground attack missile. There were also proposals for equipping a strike variant of the SR-71 with four nuclear armed Short Range Attack Missiles. At Mach 3+ the SRAM would have a range over over 500 nautical miles, but at the cost of lower accuracy, with a CEP of 1,500 feet at 100 nautical miles and 3,600 feet at 300 nautical miles. It's worth noting that the SRAM did not feature terminal guidance, and that improvements in inertial guidance systems or use of active guidance systems could have significantly improved accuracy. It seems that accuracy would likely have been insufficient for anything other than a nuclear warhead, so SR-71 air to ground aircraft would probably be assigned to Tactical Air Command or Strategic Air Command in the nuclear attack role. However, could variants have been developed with greater accuracy for use in conventional attack roles? What about using them as Reconnaissance Strike aircraft in line with their original designation, flying over enemy air defenses with anti-radiation missiles to take out enemy air defenses or force them to shut down? How would a platform like this have fared relative to the F-111 and F-117 in Vietnam, Libya, and Iraq?