Saudi Arabia’s defence minister delivered a blunt message to Iranian officials in Tehran last month: take President Donald Trump’s offer to negotiate a nuclear agreement seriously because it presents a way to avoid the risk of war with Israel.

Alarmed at the prospect of further instability in the region, Saudi Arabia’s 89-year-old King Salman bin Abdulaziz dispatched his son, Prince Khalid bin Salman, with the warning destined for Iran’s Supreme Leader Ayatollah Ali Khamenei, according to two Gulf sources close to government circles and two Iranian officials.

Prince Khalid, who was Saudi ambassador to Washington during Trump’s first term, warned Iranian officials that the U.S. leader has little patience for drawn-out negotiations, according to the four sources.