on the OPEC member nation , including curbingProhibitingits crude-oil exports to the U.S. , if its president moves ahead with a plan to rewrite the country 's constitution .
The memo , sent by the White House to the U.S. State Department , paves the way for U.S. efforts to curbCause.movement.down.lossIranian oil exports after Washington 's decision to pull out of the 2015 deal between Iran and six world powers curbingProhibitingTehran 's nuclear program .