Witkoff delivered the message during a private donor meeting in Washington ahead of renewed negotiations in Geneva.

The demand targets the "sunset clauses” in the Joint Comprehensive Plan of Action, negotiated under former President Barack Obama. Those provisions allowed certain limits on Iran’s uranium enrichment, centrifuge development and stockpile size to expire gradually between eight and 25 years after implementation. 

President Trump has long argued that the phased expiration weakened the agreement’s long-term effectiveness.

According to one source briefed on the meeting, Witkoff said U.S. negotiators are approaching talks "from the premise that there are no sunset provisions,” adding that any Iranian commitment must be enduring. The position sets a higher bar for diplomacy as American and Iranian officials prepare for discussions expected to focus on whether Tehran can continue limited enrichment on its soil and how its existing stockpile of enriched uranium would be handled.

Iranian Foreign Minister Abbas Araghchi left Tehran on Wednesday for what Iranian state media described as the third round of indirect negotiations. He said Iran is entering the talks determined to secure a "fair and balanced” agreement. President Masoud Pezeshkian expressed cautious optimism about the diplomatic track.

U.S. officials confirmed Witkoff and senior adviser Jared Kushner will attend Thursday’s session. 

Trump has reiterated his preference for diplomacy while warning that Washington retains alternative measures to prevent Iran from acquiring a nuclear weapon. 

Analysts say the insistence on permanent limits could strengthen the deal’s durability in Washington but may complicate efforts to secure Iranian consent.