Iran has been at war with the "Great Satan" (USA) since the establishment of the Islamic Republic in 1979. Its opening move was the regime's seizure of the American Embassy and its taking U.S. diplomats hostage for 444 days in 1979-1980. Technically, the move was an internationally recognized casus belli, legitimate cause for war.
In addition, the Iranian regime's proxy terrorist group, Hezbollah, engineered the murder of 241 U.S. soldiers, sailors, and marines in Lebanon on October 23, 1983. Iran also sponsored the truck bombing that murdered 19 US Air Force personnel at the Khobar Towers housing complex in Saudi Arabia on June 25, 1996, in an attack allegedly executed by a Bahrain-based cell of Hezbollah, with the cooperation of a Saudi-trained Hezbollah cell.
Iran was behind the September 11, 2001 World Trade Center and Pentagon attacks. The Islamic Republic's intelligence services facilitated travel across Iran by several of the hijackers in the weeks leading up to 9/11.
Additionally, after the 9/11 attacks, Iran granted refuge, reconstitution, and a base of operations for several high-level al-Qaeda terrorists.
After the overthrow of Saddam Hussein in April 2003, when Tehran activated its underground intelligence network in Iraq to target American troops, Iran was responsible either directly or indirectly for about a third of U.S. casualties in Iraq.
The Islamic Republic also has given military assistance to the Afghan Taliban to kill U.S. and coalition troops in Afghanistan.
Iran's Islamic Revolution Guard Corps (IRGC) naval assets have repeatedly instigated confrontations with U.S. naval ships in Persian Gulf waters.
IRGC gunboats also have threatened commercial shipping, as well as U.S. and allied military assets in Persian Gulf waters, including the Strait of Hormuz. In late April 2015, Iran seized the Marshall Islands-flagged vessel Maersk Tigris, and detained the ship and crew for weeks. In July, several IRGC gunboats surrounded the U.S.-flagged Maersk Kensington.
The most recent Iranian provocation reportedly occurred this month, on August 4, when an Iranian Navy Vosper Class frigate pointed a deck-mounted machine gun at an American helicopter that had just landed on an allied warship.
Tehran's assistance to the Shia Houthi tribesmen in Yemen has enabled Iran to expand its territorial control of the country. If the Houthi become the dominant force in Yemen, Iran would be in a position to threaten shipping in the Bab el-Mandab Strait, a maritime chokepoint between the Persian Gulf and the Red Sea. A blockade there, as well as at the Strait of Hormuz on the other side of the Arabian Peninsula, would be a clear violation of freedom of navigation on the high seas, a vital international interest acknowledged by the U.S.
Iran has also taken its offensive against the United States to the Western hemisphere. Iran has forged intelligence relationships with several Latin American countries that do not have friendly diplomatic relationships with the U.S., such as Cuba, Venezuela, Ecuador, Nicaragua, and Bolivia.
Hezbollah, Iran's proxy terrorist group, has also infiltrated parts of the United States, with sleeper cells in Dearborn, Michigan; Charlotte, North Carolina; and several other locales.
On a strategic political plane, Iran probably believes that it has been able to drive a wedge between the U.S. and its ally, the "Little Satan," Israel, over the Obama Administration's effort to forge a negotiated nuclear treaty with the Iran.
This strategy has also been applied to America's political and military alliances with the conservative Sunni Arab governments on the Arabian Peninsula.
The IRGC also continues to manage several weapons-development projects, including intercontinental ballistic missile (ICBM) systems capable of launching nuclear-armed re-entry vehicles at the continental United States.
It seems clear that despite the American political establishment's failure to recognize that a state of war already exists between Iran and the United States, the Islamic Republic has no doubt with whom it is at war.
The diminution of American influence in the region, the destruction of the "Zionist Entity" (Israel), and challenging the legitimacy of Sunni Arab Gulf monarchies appear to be the main motive forces driving Iran's foreign policy.
The regime's hardliners use their hostility to the "Great Satan" (America) to demonstrate their loyalty to the Islamic Revolution.
U.S. policymakers who hope that the nuclear deal will help nudge the Islamic revolutionary state into becoming a normal member of the international community seem to forget the past. Policymakers, journalists, and intelligence analysts had all predicted that the era of former Iranian President Mohammad Khatami was a sure sign of the evolution of the revolution. Khatami was replaced by the even more hardline president, Mahmoud Ahmadinejad.
Dr. Lawrence A. Franklin was the Iran Desk Officer for Secretary of Defense Rumsfeld. He also served on active duty with the U.S. Army and as a Colonel in the Air Force Reserve, where he was a Military Attaché at the U.S. Embassy in Israel.
 Congressional Testimony in 2002 by FBI former Director Louie Freeh and NPR radio interview and U.S Federal Court Testimony. Freeh accuses Iran's Ministry of Intelligence of supervising truck bomb attack on Khobar Towers in Dhahran, Saudi Arabia citing several Saudi citizens and a Lebanese Hezbollah operative.
 "The Secret War with Iran" by Ronen Bergman. Free Press, N.Y. 2007. p.195.
 US District Court Rules Iran Behind 9/11 Attacks." District Court Judge George B. Daniels, in a decision handed down on 15 December 2011, ruled in Havlish et al v. bin-Laden et al that Iran and Hezbollah materially and directly supported al Qaeda in the September 11, 2001 attacks on the United States.
 See comments of former DIA Director LTG Michael Flynn and seized Bin Laden documents that detail the relationship, as well as Ronen Bergman's chapter on links between Al-Qaeda and Iran.
 9/11 Commission Report.
 U. S. Ambassador James Jeffrey believes that at least a quarter of U.S. combat deaths in Iraq are attributable to Iran. 26 August 2010. Reuters. Other estimates reach the one-third figure.
 "Dem Congressman on Iran Sanctions Relief: 'They'll Have a Few Billion Left over to Kill Americans'" by Daniel Greenfield, FrontPageMagazine.com, July 15, 2015. The article quotes former member of the Pentagon's Joint Improvised Explosive Device defeat Organization that 500 U.S. combat deaths in Iraq and Afghanistan attributed to Iran is probably on the low side.
 "The Secret War with Iran" by Ronen Bergman, p.205. "Al-Mabarrat – A Hezbollah Charitable Front in Dearborn, MI?" by Steven Emerson 22 July 2006.
 Supreme Leader Khamenei has just published the book "Palestine," in which he writes that one objective of Iranian statecraft is to encourage "Israel Fatigue" in America re its alliance with the "Zionist Entity,"
 Several articles on Arab Gulf allies of U.S. having qualms about possible U.S. shift toward an era of cooperation with Iran. For example: "Like Israel, U.S. Arab Allies Fear Obama's Iran Nuclear Deal" by Yaroslav Trofimov, Wall Street Journal, 4 March 2015; "Why Arab Countries Fear the Iran Deal" by Geneive Abdo, The National Interest, 7 April 2015.
 Several late July/early August 2015 Congressional hearings, Senate Armed Services Committee, on Iran's ICBM programs.