(credit for all pictures goes to Yefim Gordon and Sergey Komissarov)
Interestingly, it appears that this design was intended to be able to operate in both manned and unmanned modes.
In Unflown Wings, it is mentioned that the Tu-2000 would have featured up to six turbojet engines (in addition to liquid fuel rocket engines), in order to improve in-atmosphere performance. Interestingly, it is also mentioned that use of a nuclear rocket engine was considered, due to its higher specific impulse compared to chemical engines. This is probably the first time I have heard of a nuclear engine being proposed for such an application.
There is also brief mention in Unflown Wings of a MiG designed spaceplane named 'Oryol'. This was intended to be ground launched, with one proposal having it launched by an electromagnetic mass driver. However, it was seen as less technically feasible than the AKS, and was not developed as far.