Trump has denigrated this deal from its inception, now he pulled the plug. In his normal fashion, he left a door open for negotiations. It has become well known that he begins the negotiations making unrealistic demands only to reach an agreement by conceding the most egregious of the demands.
Mnuchin followed with the announcement that “Sanctions will be reimposed subject to certain 90 day and 180 day wind down periods. At the conclusion of the wind down periods, the applicable sanctions will come back into full effect. This includes actions under both our primary and secondary sanctions authorities”.
The other members included in the original deal remained committed to the deal. Trump’s position to these countries was to warn them that if they continue to transact with Iran, they will be subject to sanctions. Iran has made the initial decision to unilaterally withdraw from the deal. But this action may affect their ability to export oil and increase its risk of an attack from Israel.