US Vice-President JD Vance has claimed Washington is "very close" to reaching a deal with Iran to bring the war to an end.
Vance told the BBC it was too early to say "when or if" an agreement would be finalised, but suggested the parties were getting closer, with the framework of a deal agreed pending sign-off from the respective leaders.
The Vice-President said on Thursday negotiators were "going back and forth on a couple of language points", including the "question of enrichment".
He told reporters: "We're not there yet, but we're very close and we're going to keep on working at it."
While Vance said the US believed the Iranians were negotiating in "good faith", President Donald Trump and other officials have cautioned that "option B" - the resumption of military combat operations - is still very much on the table.
Among Washington's demands in negotiations are that Iran cease producing highly enriched uranium and dispose of existing supplies, and the reopening of the Strait of Hormuz - a key global shipping route.
Its closure since the beginning of the conflict has caused turmoil in global markets with oil prices sent soaring and fluctuating wildly since.
Since a ceasefire was agreed between the nations on April 8, Trump has repeatedly made claims about being close to a deal to end the conflict.
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