This is due partly to the relatively high domestic rates for these two countries compared to U.S. domestic rates and partly to the disparity in the mail volumes exchanged between the U.S. and these two countries.
The U.S. is considering raising the domestic rates to match the rates of these two countries.
mnli hypothesis: The U.S. is considering raising the domestic rates to match the rates of these two countries. premise: This is due partly to the relatively high domestic rates for these two countries compared to U.S. domestic rates and partly to the disparity in the mail volumes exchanged between the U.S. and these two countries.