US President Donald Trump on Wednesday ruled out that Russia or China could take control of Iran's stockpile of enriched uranium as part of a possible agreement to end the war. "No, I would not be comfortable with that," the president replied tersely to journalists who asked about the possibility of Moscow or Beijing taking custody of the radioactive material with which Tehran could potentially build a nuclear weapon. The statement introduces a new complication into the negotiations both parties are conducting in Doha under Qatari mediation.