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Absent the waivers, the U.S. might have been obliged under a 2011 law to punish China for additional purchases by taking steps to cut it off from the U.S. financial system. Such a move could have led to a major disruption of the U.S.-China relationship, which has already been under strain in connection with disputes over the American military presence in East Asia, accusations of human rights abuses in China and other issues.
Mark Dubowitz, an energy specialist at Foundation for Defense of Democracies, said some industry officials believe that a few Chinese companies are still trying to quietly purchase Iranian oil, which is moving covertly in tankers. But he said the administration has decided "they would be better off trying to work this out quietly with China."
The new U.S. sanctions came fully into force on Thursday. On Sunday, the European Union is set to impose a blanket ban on purchases of Iranian oil by its member states and a ban on the sale of the insurance needed to underwrite tankers carrying Iranian oil.
U.S. officials noted that exports of Iranian oil fell from 2.5 million barrels a day last year to 1.5 million barrels per day for the first months of 2012, according to the International Energy Agency.
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