Premise 1) The US has a great ability to acquire debt.
Premise 2) The US is running an annual budget deficit exceeding $1trillion this year
Premise 3) Many nations and people in the world can be assisted with more money
Conclusion: The US has a moral obligation to continue to increase its deficit in order to assist the people in the world (via wars, via financial aid to foreign nations, via domestic grants, via tax breaks [for both those making less than the median income and at the corporate level]).
Are we morally obligated to give what we do not have yet, under the assumption that we can earn it in the future?
I for one do not take out a line of credit on my house, despite my ability to, to make large charitable contributions. And I would consider it illogical to call me immoral for not doing so.