US is not willing to give millions, let alone billions of Dollars to Pakistan for anything. Again check the numbers, and then the humanitarian challenge. It is not even peanuts. The Afghan refugee situation today is because Pakistan was left high and dry ,as soon as Soviets left, to fend for the refugee problem itself, for all intents and purposes, and so they could not be successfully repatriated.What the US(and allies combined) gave during Afghan war mostly went to the war effort, and that too seized as soon as Soviets left. Compare it with the Mexican situation the US has and the amount of money they need for that.