We need airlift capability to land a hundred thousand troops anywhere on Earth in ten days. Example: Eastern US to Afghanistan is 7000 nautical miles. without forward refueling bases, our airlift capability is screwed. The C-17 has a range of 2800 nm and would need to be refueled twice to get there, plus again immediately after take off from the combat theater. We need tankers which can fly with the airlift and refuel aircraft as needed.
Boeing's 777 has a range of 8000 nm and can take off with a grand total of 400,000 lbs of fuel in both wings and fuselage. Airbus's A330-200, aka KC-45, has a range of 7000 nm and can take off with a grand total of 240,000 lbs of fuel in both wings and fuselage (maybe 300,000 if they strip more weight off). For comparison, the KC-135 has a range of 3000 nm and can take off with a grand total of 220,000 lbs of fuel in both wings and fuselage. The Airbus A330-200, aka KC-45, is thus equivalent to the KC-135. Neither will be enough to refuel C-17's in a massive, long distance airlift which is deprived of forward air base refueling.
We need massive refueling ability! Something bigger, perhaps, than the Airbus A380-F which has a range of 5600 nm and can take off with a grand total of 740,000 lbs of fuel in both wings and fuselage; and something which perhaps could land on 1000 meter US Navy refueling platforms.
The tanker we really need is Boeing’s 747-8 with a range 8000 nm and which can take off with a grand total of 560,000 lbs of fuel in both wings and fuselage. Maybe with a decent Republican President and Congress we could get a few hundred of those.