Iran has agreed to allow International Atomic Energy Agency (IAEA) inspectors back into the country, marking a significant de-escalation in tensions between Tehran and Washington.
Vance announced the development on Monday, stating that recent negotiations with Iranian delegates have yielded substantial progress.
The agreement to restore monitoring access is viewed as a critical step toward stabilizing the region's nuclear outlook.
Markets reacted swiftly to the news, with risk sentiment improving across global equities and energy sectors.
The prospect of reduced geopolitical friction in the Middle East has helped alleviate supply disruption fears that have weighed on oil prices and shipping routes.
Brent crude futures softened as traders adjusted to the lower probability of immediate conflict or sanctions escalation.