"It is worrying that Iran is choosing to continue to escalate its nonperformance of its JCPOA (Joint Comprehensive Plan of Action) commitments, especially with experiments that have value for nuclear weapons research," State Department Spokesperson Ned Price told reporters.
He added, "It's another unfortunate step backwards for Iran, particularly as we, for our part, have demonstrated our sincere intention and willingness" to return to the 2015 nuclear deal.
He stressed, "We have made clear that such provocative steps would not and will not provide Iran with any leverage in negotiations." He added, "Instead, they would only intensify our concerns with Iran's activities." "We continue to urge Iran to stop this brinksmanship, to return to Vienna prepared for real talks, and to be in a position to be prepared to finish the work that we have started in April that has now taken place over six rounds," he remarked.
He noted "the window for diplomacy remains open."