"Successive Administrations have identified Iran as a key national security challenge, citing Iran's nuclear and missile programs as well as its long-standing attempts to counter many U.S. objectives in the region. Director of National Intelligence Dan Coats, in his May 11, 2017, annual worldwide threat assessment testimony before Congress, described Iran as 'an enduring threat to U.S. national interests because of Iranian support to anti-U.S. terrorist groups and militants, the Asad regime [in Syria], the Huthi rebels in Yemen, and because of Iran's development of advanced military capabilities.' Successive National Defense Authorization Acts (NDAAs) require an annual report on Iran's military power, which has in recent years contained assessments of Iran similar to those presented by the intelligence community."
CRS Report for Congress, R44017
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html