Getting moving now is often more valuable than moving fast.
I'm assuming this is a surprise, and the scientist runs into the ready room and say "I gotta go right now" Otherwise, if the move is expected and nation-states have a couple days to pre-position airplanes, then it's just too easy - Russian Blackjacks are stationed only a couple hours away at Engels AFB, and it would be easy enough to get B-1-B's from the US.
So you are probably better off going Right Now with aircraft already on base, rather than wait for a fast aircraft to be marshaled from somewhere else.
And you're in luck. That base has loads of KC-135's, which (with its 707 brother) are as fast as jetliners get, flying Mach 0.9. It'd fly at max speed and pay the fuel-economy penalty for doing so; fuel isn't a problem since it's a tanker.
And they're roughly the size of a 737/A320, so lots of airports can handle them. That matters because they can fly the cargo closer to the actual destination.
It defeats the purpose of flying supersonic if the supersonic aircraft can only land at an airport an hour further away by road.
The base also has F-15s good for 3000 miles one-way at best ferry speed. However, Berlin/London is 1500/2000 miles distance, so that's not a lot of extra fuel to be doing a whole lot of supersonic flight. Probably not worth the trouble, unless the F-15 was ready to go right now and the KC-135 was not.