U.S. President Donald Trump's unilateralism is reshaping the world in profound and irreversible ways. He is undermining the working of multilateral institutions. Other countries, for their part, no longer regard the United States as a reliable alliance partner and feel impelled to develop their own geopolitical capabilities.
Now the Trump administration is eroding the dollar's global role. Having unilaterally reimposed sanctions on Iran, it is threatening to penalize companies doing business with the Islamic Republic by denying them access to U.S. banks.
The threat is serious because U.S. banks are the main source of dollars used in cross-border transactions. According to the Society for Worldwide Interbank Financial Telecommunication (SWIFT), dollars are used in nearly half of all cross-border payments, a share far greater than the weight of the U.S. in the world economy.