Heavy tanks can overwhelm a medium power's deployment system

Why reject the M1 Abrams or Leopard 2 for a globally deployable British tank force?

Their combat performance is strong, but moving and sustaining them abroad requires a logistical system that is easier for the United States or an allied deployment to absorb.

The M1 Abrams and Leopard 2 are treated as capable tanks whose logistical demands matter as much as their combat performance. A medium power trying to deploy them worldwide would need fuel, maintenance, transport, and support on a scale that the United States can sustain more readily. Operating alongside an existing American deployment could share that burden, but an independent expedition would be much harder. The answer turns a purchase choice into a force-design question about the whole support system behind a tank.