In 2015 a landmark deal between Iran and Western powers ended one of the most tense diplomatic stand-offs.
But as relations with its Middle Eastern rival Saudi Arabia deteriorate, over the execution of a prominent Shia cleric, is it all diplomatic posturing or is there real potential for armed conflict?
We look at facts behind one of the biggest players the Middle East:
- Iran's active forces number 523,000, including the Revolutionary Guards (IRGC). (IISS, 2013)
- The Iranian defence budget as of 2013 was $23.9bn
- Saudi Arabia’s military outspends the Islamic Republic's 5-to-1.
- Iran's Ghadir Class Midget Submarines pose a threat to the geopolitically important Straight of Hormuz, which roughly 20 percent of global oil supplies must transverse on their way to markets.
- Iran has a large stockpile of Sejjil Class Ballistic Missiles with a range of 2,000 - 2,500km.
- The IRGS's Qud's Force is a special overseas force and is said to carry out a range of highly sensitive functions including intelligence, special ops, arms smuggling and political action.
- The United States could destroy all key elements of Iranian military power in virtually any scenario in a matter of weeks, if Washington had the support of Iran’s neighbours. It could inflict devastating damage in a matter of days.
- Iran commandeered and captured an American Lockheed Martin RQ-170 Sentinel using cyber warfare.
- The Supreme Leader of Iran, Ayatollah Khamenei, has said that the possession of nuclear weapons is a “grave sin”.
- The Iranian president said Iran `never sought ... (and) will never seek to manufacture a nuclear weapon'