Above: USAF aircraft lined up at the U.S. military base at Diego Garcia
According to Iranian armed forces media outlet Defa Press (06JUN14):
Advisor to the Representative of the Supreme Leader in the IRGC Mojtaba Zonnour states that “in the event of an irrational [military attack] by the United States, America’s military bases will not be safe from our missiles, whether in Bahrain or at Diego Garcia in the Indian Ocean.”The advisor went on to state that such a policy was in response to the American policy of “all options are on the table,” where referring to the Iranian nuclear program.
It has been surmised by some military thinkers here in the West that Iranian efforts at increasing the range of their conventional ballistic missiles were not, as some alarmists had thought, to target population centers in Europe or even North America, but instead were aimed at targeting the United States strategic military base at Diego Garcia. The advisor’s statement appears to confirm this latter interpretation.
Moreover, while the advisor's statement may infer an Iranian strike capability, more likely it may serve to indicate an IRGC-ASF design intent for more capable ballistic missiles, in terms of enhanced range and accuracy.
In the event of war with the United States, disruptions--even temporary ones--as well as negatively impacting American military prestige, would no doubt form the crux of Iranian asymmetric warfare. It should be assumed military thinkers in Iran conceive of the base at Diego Garcia in terms of fulfilling such criteria, as a second-strike target of war.