Iran’s Revolutionary Court sentenced an Iranian-American to death for espionage today. A former US Marine who served in Iraq and Afghanistan, Amir Mirzaei Hekmati, is accused of receiving training from the US Central Intelligence Agency and attempting to infiltrate Iranian intelligence services. Mr. Hekmati said that he was only in Iran to visit his grandmother and denied all charges of spying.

News of the conviction comes at a time when tensions between the US and Iran are already high. Most recently, Iran threatened to close the Strait of Hormuz, a critical waterway for global energy supplies, and the situation with Hekmati is likely to strain relations still further.