BERLIN—Iranian demands for guarantees from the U.S. have once again stalled efforts to revive a 2015 nuclear pact, leaving Washington and European capitals unsure if a deal is possible.
Tehran on Monday sent a response to the European Union, which chairs the nuclear talks, neither accepting nor rejecting an EU draft text of a deal but raising several issues Iran wanted incorporated into the agreement. The EU had said its draft was the “final text” of a possible deal when it sent it out, announcing that negotiations were over.