New Delhi, June 17 -- The emerging agreement between the Trump administration and Iran is being presented by its supporters as a diplomatic achievement and by its critics as a strategic concession. Yet from an Indian perspective, the debate should not focus solely on the agreement's details. The larger lesson is far more important. Regardless of whether the deal succeeds or fails, it reinforces a reality India has understood for decades: great powers ultimately act in their own interests, not those of their partners.

This is not a criticism unique to the United States. It is a fundamental truth of international politics. Nations pursue policies that serve their domestic priorities, economic needs, electoral calculations, and strategic ob...