Iran has agreed to allow International Atomic Energy Agency (IAEA) inspectors back into the country, marking a significant shift in its nuclear posture.
Vance announced the development, describing it as a concrete step forward in ongoing diplomatic efforts between Washington and Tehran.
The agreement reverses a policy adopted by Iran in the wake of the 2025 war with Israel, during which Tehran initially severed ties with the nuclear watchdog.
The readmission of inspectors is widely viewed as a prerequisite for broader negotiations aimed at curbing Iran's nuclear program and reducing regional instability.
Markets reacted positively to the news, with risk sentiment improving as investors priced in a lower probability of renewed military escalation in the Middle East.
Energy markets, which had been volatile due to fears of supply disruptions, saw a modest decline in prices as the immediate threat to shipping routes and production facilities appeared to recede.