The United States has said it has observed evidence that Iran is attempting to rebuild its nuclear program, Vice President J.D. Vance announced on Wednesday, raising tensions ahead of renewed negotiations with Tehran.
Speaking a day before scheduled talks in Geneva between U.S. and Iranian delegations on the nuclear issue, Vance said Washington believes Tehran is seeking to restart nuclear activities despite earlier U.S.-led strikes that targeted Iranian nuclear sites in June 2025.
“The principle is very simple: Iran cannot have a nuclear weapon,” Vance told reporters, underscoring the U.S. position that Tehran should not pursue nuclear development that could be diverted toward weapons.
Vance’s remarks echoed comments by U.S. officials including Senator Marco Rubio, who said Iran was attempting to reconstruct elements of its nuclear programme after being warned against doing so following last June’s attacks.
The U.S. government has built up a significant military presence in the Middle East ahead of the talks, with senior administration figures indicating that diplomatic engagement will be accompanied by military readiness if Tehran fails to comply with U.S. demands.
U.S. envoys Steve Witkoff and Jared Kushner are due to meet Iranian negotiators, with Washington insisting any agreement must include strict and enduring constraints on Iran’s nuclear activities.
Tehran has not publicly acknowledged attempts to rebuild its programme and maintains that its nuclear work is for peaceful purposes, while denying U.S. allegations. Iran’s foreign ministry has previously criticised U.S. claims and called for negotiations without coercive pressure.
The Geneva meetings come against a backdrop of deep mistrust between Washington and Tehran following the June 2025 strikes and ongoing disagreements over sanctions, enrichment limits and broader security issues in the Middle East.