One of the most extreme measures would be to cut off Russia from the system of international payments known as SWIFT that moves money around the world, as was done to Iran.
In 2019, the Russian prime minister at the time, Dmitri A. Medvedev, labeled such a threat as tantamount to “a declaration of war.”
Maria Shagina argued in a report for the Carnegie Moscow Center that such a move would be devastating to Russia, at least in the short term. “The cutoff would terminate all international transactions, trigger currency volatility, and cause massive capital outflows,” she wrote this year.
The SWIFT system, which is based in Belgium, handles international payments among thousands of banks in more than 200 countries.
Since 2014, Moscow has taken steps to blunt the threat by developing its own system to process domestic credit card transactions, she noted. But it is another measure that would affect European countries more than the United States because they do so much more business with Russia.
Several economic and political analysts have said restricting access to SWIFT would be a last resort.
Arie W. Kruglanski, a psychology professor at the University of Maryland, said that in assessing the impact of sanctions, economists too often overlook the crucial psychological aspect.