The latest U.S. negotiation proposal has "narrowed the gaps" between U.S. and Iranian demands, though some gaps remain, according to the Iranian Students' News Agency cited by Bloomberg on May 21. Furthermore, Iranian Supreme Leader Mojtaba Khamenei reportedly issued a directive that Iran's highly enriched uranium stockpiles are to remain in the country.

On May 20, the U.S. military said it had boarded an Iranian-flagged tanker in the Gulf of Oman suspected of trying to evade the U.S. blockade of Iranian ports. The following day, President Donald Trump stated he was willing to wait for the "right answer" from Iran, but also noted that talks were "on the borderline" between continuing negotiations and resuming fighting.