In increasingly alarming scenes, the United States and Iran are facing off in the Middle East. Tensions have been escalating steadily for the last two months, driven by concerns over the Islamic Republic's nuclear capabilities.There are concerns that the two nations are headed towards military conflict.The key figure in Iran's strategic manoeuvring, and one of the most powerful military figures in the Middle East, is a shadowy figure in Iran's feared Revolutionary Guard.In this timely program from the BBC, a portrait of Iran's military ambitions, and the man masterminding them emerges.