Economic considerations color every aspect of international dealings, and nations are just like individuals in that the lender sets the terms of its dealings with the borrower.
Premise 1
Economic considerations color every aspect of international dealings.
Premise 2
Nations are like individuals: the lender sets the terms of its dealings with the borrower.
Conclusion
Therefore, a nation that owes money to another nation cannot be a world leader.
Evaluate
The argument moves from "the lender sets the terms" to "the borrower cannot be a world leader." The missing link: a nation cannot be a world leader if another nation sets the terms of its dealings. Without that connection, the lender-borrower relationship has no implication for world leadership.
Goal
The correct assumption should connect "having one's terms set by another nation" to "cannot be a world leader."