For millennia, Iranian leaders have perceived strong naval forces as crucial to securing foreign trade and cementing the country’s predominance in the strategic Persian Gulf. Furthermore, given Iran’s huge size, long history, and strong national identity, its leaders have seen themselves and their maritime presence as the guarantor of regional security and the presence of foreign troops in the region as its impediment. Iranian strategists learned important lessons from the direct confrontation with the technologically superior US Navy at the end of the war with Iraq. Based on these lessons, since the 1980s, Iran has maintained two naval forces – the Islamic Republic of Iran Navy (IRIN) and the Islamic Revolutionary Guard Corps Navy (IRGCN) – which are examined in detail in this chapter.