United States Vice President JD Vance is poised to take on his biggest role yet on the international stage as President Donald Trump’s chief negotiator to end the three-month war with Iran, a moment that could shape Vance’s prospects as a White House successor. The two nations agreed to a provisional peace agreement on Wednesday that suspended hostilities but left core issues unresolved, deferring decisions on Iran’s nuclear programme, its support for regional groups and the economically vital Strait of Hormuz to 60 days of talks. The discussions are a high-risk scenario for all sides in the conflict, the broader Middle East, and for Vance’s political ambitions.