Congress can enforce a halt to President Trump’s Iran policy only by enacting a concurrent resolution approved by both chambers that overrides a veto, or by withholding funding in the coming budget.
President Donald Trump has drawn heavy criticism for the unilateral military steps he has taken as Commander in Chief against Iran’s militant factions: (1) carrying out strikes against Iran, (2) blocking the Strait of Hormuz to Iranian oil shipments, and (3) pursuing what I anticipate will be a successful bid to compel Tehran to yield. In substance, Trump’s current approach toward Iran amounts to a timely assertion of U.S. military power—paralleling actions historically taken by Presidents Thomas Jefferson and James Madison against the Barbary pirates, conducted without prior congressional authorization, between 1801 and 1815.
The Barbary pirates served as an early-19th-century analogue to what some regard as Iran’s contemporary militant regime. They targeted American and European merchant vessels and enslaved their crews. Estimates suggest that more than a million sailors from America and Europe were sold into slavery by these raiders over the centuries during which they preyed on Western shipping. Robert Davis, British Slaves on the Barbary Coast, BBC (February 17, 2011). The Barbary pirates operated out of Libya and other parts of North Africa until France annexed Algeria in 1830.
Congress did not declare war on the Barbary pirates, but Presidents Jefferson and Madison properly exercised their unilateral Commander-in-Chief powers to dispatch American ships and Marines to subdue them through the use of force. This effort defeated the Barbary threat, and the Framers—many of whom were still alive from 1801 to 1815—acquiesced in the constitutionality of this unilateral presidential deployment of military force. Since 1789, the United States has fought only five wars that were formally declared: the War of 1812, the Mexican-American War, the Spanish-American War, World War I, and World War II. Yet U.S. Presidents, acting as Commanders in Chief, have unilaterally deployed the armed forces on numerous other occasions.
Presidents have deployed the U.S. military without explicit authorization from Congress on at least 125 occasions similar to the Barbary episode (1801-1815). Some of these engagements have been profoundly deadly, such as the Korean War (approximately 33,700 battle deaths), the Vietnam War (which saw U.S. involvement despite later withdrawal of congressional authorization from 1971 to 1975, with about 3,246 battle deaths), and the 2011 operation to topple Libyan dictator Muammar Gaddafi under President Obama (which included the death of a U.S. ambassador). These interventions were not formally authorized by Congress but were funded by it. See John C. Yoo & Robert J. Delahunty, The President’s Constitutional Authority to Conduct Military Operations Against Terrorist Organizations and the Nations that Harbor or Support Them. In addition, four undeclared wars with some form of congressional authorization occurred during my lifetime: the Vietnam War (1964-1971), the Gulf War (1991), the Afghan War (2001-2021), and the Iraq War (2003-2011). The historical gloss on the constitutional text supports the kinds of actions President Trump is undertaking today.
After 237 years of practice, constitutional law is settled on the point that presidents possess the authority to employ the U.S. military without Congress’s permission to subdue pirates and terrorists—figures such as the late Ayatollah Ali Khamenei, who could be described as a contemporary pirate. Iran has been a significant challenge for the United States since its Islamic Revolution of 1979.
Iran seized and held hostage the U.S. Ambassador to Tehran and more than 50 other American embassy personnel from November 1979 to January 20, 1981. It was responsible for the 1983 terrorist assault on a U.S. Marine barracks in Lebanon, which killed 241 American service members. For the past fifty years, Iran has financed a number of Islamic militant organizations across the Middle East, including Hezbollah in Lebanon, Hamas in the Gaza Strip, and the Houthis in Yemen—groups that have attacked Israel and Saudi Arabia, both American allies, as well as U.S. military personnel in the region.
The Ayatollah Khamenei has appeared intent on destroying Israel with a nuclear weapon, and Iran has been developing ballistic missiles capable of striking Europe today and possibly the United States in the long run. He routinely led crowds that denounced America as the “Great Satan” and chanted “Death to America.” Chain-reaction reluctance to address Iran was unwise under the leaderships of the second Bush, Obama, and Biden administrations.
Trump stands out as the first President since 1979 who has demonstrated the resolve to halt Iranian terrorism—an updated form of piracy in the Strait of Hormuz, a critical chokepoint in the global oil supply. He deserves pronounced praise for taking this step. The American embargo on Iranian oil exports is likely to compel Iran to surrender unconditionally, which would bring about the necessary termination of Iran’s nuclear ambitions and its practice of tolling ships in international waters near the Strait of Hormuz (an activity Iran has no right to undertake). At the just-concluded summit, China’s Xi Jinping aligned with President Trump on three points: (1) Iran cannot be trusted with nuclear weapons, (2) Iran cannot charge tolls on ships transiting through the Strait of Hormuz, and (3) Iran should immediately end its shipping blockade. The two most powerful militaries on the planet are in complete agreement on this matter.
If regime change does occur in Iran—as I anticipate if the United States maintains course—Washington can assist Iran in expanding its oil and natural gas production, much as the United States is attempting to do in Venezuela by removing Nicolás Maduro from power. When that scenario unfolds, crude prices are likely to plummet, possibly to around $40 per barrel in the near term, which could push Vladimir Putin’s corrupt regime toward collapse and help bring the Ukrainian conflict to a conclusion favorable to Ukraine. Americans should be patient and allow the blockade to achieve its aims. Iran cannot sustain itself on less than 10 percent of its budget, which, in the long run, depends on oil and gas sales.
The Constitution vests executive power solely in the President, who is the Commander in Chief. From George Washington’s deployment of troops to quell the Whiskey Rebellion, to Jefferson and Madison’s use of the Navy and Marines to suppress the Barbary pirates, to Lincoln’s use of military force to win the Civil War, to Truman’s use of the armed forces to prevail in Korea, to Obama’s use of airpower to topple Muammar Gaddafi in Libya, Americans have long understood presidential war powers as permitting action without prior congressional approval to counter terrorist threats or pirate threats.
Congress possesses two powers—the declaration of war and the grant of letters of marque and reprisal—that are meant to influence the international obligations of our allies and authorize privateers to seize enemy ships as prizes. These powers do not bar the President from directing armed forces in the situations described above. It would be unconstitutional for either house of Congress to enact legislation designed to halt Iran-related hostilities, given that the President alone holds the executive authority, including the Commander-in-Chief role. For a more thorough discussion of these constitutional arguments, see Robert Delahunty & John Yoo, Making War, 93 Cornell Law Review 123 (2007), as well as their other writings on presidential war power.
Of course, Congress could constitutionally stop President Trump by cutting off funding for operations tied to Iran. But, for the practical reasons outlined above, such a move would be imprudent. Yes, domestic gas prices are temporarily elevated. Yet if the blockade remains intact, regime change in Iran is likely and oil and gas prices will fall rapidly in the near term. Still, restricting funding would be within Congress’s power; any statute ordering the President to halt hostilities or prematurely end the blockade would exceed Congress’s authority. And it would prematurely end a significant confrontation with a group of pirates and thugs who lack broad support among the Iranian people.
