Media Guide: The 2001 Authorization for Use of Force (AUMF)

By Research Fellow Andrew Lumsden

In the context of escalating tensions between the United States and the Islamic Republic of Iran, a bipartisan group of six U.S. Senators sent a letter to President Donald Trump on June 18, 2019 bluntly warning that “Congress has not authorized war with Iran and no current statutory authority allows the U.S. to conduct hostilities against the Government of Iran.” The signatories of this letter, among other U.S. lawmakers, have expressed concern that the Trump Administration may utilize a nearly 20-year-old law to initiate military action against Iran without Congressional approval.

This Media Guide will explain the 2001 Authorization for Use of Military Force (AUMF), how has it impacted America’s post-9/11 foreign policy and the possibility that it may play a role in a potentially escalating U.S-Iran conflict.

What is the AUMF?


Although the President of the United States is the Commander-in-Chief of the country’s armed forces, the Constitution and legislation limits his power to send U.S. troops into combat. The U.S. Constitution gives Congress alone the power to declare war, and the War Powers Act of 1973, passed during the Vietnam War, places strict limitations on the President’s ability to deploy troops absent a formal declaration of war, including regular reporting and Congressional consultation and consent requirements.

On September 11, 2001, the Islamist terrorist group al-Qaeda launched attacks on the United States which resulted in the deaths of some 3,000 people. Three days later, the U.S. Congress passed the Authorization for Use of Military Force, which gives the President the power to use “necessary and appropriate force against those nations, organizations, or persons he determines planned, authorized [or] committed” the 9/11 attacks, or “harbored” any organizations or individuals who did without further Congressional approval. Having been passed at a time when the origins and perpetrators of the 9/11 attacks were not fully understood by U.S. officials, the language of the AUMF was deliberately left open-ended. No groups or countries were specified, and no timeframe or expiration date was set.

How and when have U.S. Presidents used the AUMF?

The AUMF was first invoked in late September and October 2001 by President George W. Bush to authorize the U.S. invasion of Afghanistan, where al-Qaeda had been based with the permission of the Taliban, an Islamist faction which ruled the country. The Bush Administration would invoke the AUMF another 16 times during its time in office to initiate or continue U.S. military operations and troop deployments in Afghanistan, Djibouti, (the Republic of) Georgia, Iraq, Somalia, the Philippines and Yemen. The Bush Administration also invoked the AUMF for the conduct of “secure detention operations” in Guantanamo Bay, Cuba.

When President Barack Obama took office in 2009, his Administration successfully argued in federal court that the AUMF permitted the detention and targeting not only of members of the groups responsible for the 9/11 attacks, but of all “forces associated” with them. The Obama Administration continued most ongoing military and detention operations and expanded drone strikes against targets in Afghanistan, Yemen and other states in the region. Citing the AUMF under its new interpretation, the Obama Administration began launching military operations against the Islamic State of Iraq and Syria (ISIS) in 2014. Although an undeniably real and dangerous threat to U.S. security, ISIS did not exist at the time of 9/11. Between 2014 and 2017, the Obama Administration used the AUMF to justify troop deployments and military strikes associated with its anti-ISIS campaigns in Syria, Iraq, Libya and Turkey. In total, President Obama invoked the AUMF at least 19 times over the course of his eight year Administration.

The Trump Administration, since taking office in 2017, has so far invoked the AUMF in at least two reports to Congress, to justify continuing U.S. ongoing U.S. military activity and to expand U.S. operations or troop deployments in Yemen, Jordan, Kenya, Niger and Cameroon. The Trump Administration has also asserted that it interprets the AUMF as authorizing U.S. military action in defense of allies who are fighting or targeted by terrorist organizations.

In all, the AUMF has so far been invoked more than 40 times by three U.S. Presidents since 2001 to permit U.S. military action in 19 countries without Congressional debate or approval. Critics, most notably Congresswoman Barbara Lee (D-CA), the only member of either house of Congress to vote against it in 2001, have called the law a “blank check for endless war,” and lamented that it represents an ‘abdication’ of Congress’ constitutional authority to regulate executive use of the U.S. military.

Why is the AUMF relevant today?

Although some lawmakers, including Rep. Lee, have long spoken out against executive misuse of the AUMF, the law had largely fallen out of the public eye until 2019. As tensions between the United States and Iran have escalated to levels unseen in decades, there are concerns among some lawmakers in both political parties that the Trump Administration may use the AUMF to justify unilateral military action against Iran without Congressional approval.

These concerns are driven largely by the Trump Administration’s revival of accusations that Iran has harbored and colluded with al-Qaeda agents, which would allow the Trump Administration to invoke the AUMF. In his statement withdrawing the United States from the Iran nuclear deal in 2018, President Trump accused the Islamic Republic of “support[ing] terrorist proxies and militias such as…the Taliban, and al Qaeda.” In April 2019, Secretary of State Mike Pompeo accused Iran of “no doubt” colluding with al-Qaeda, telling the U.S. Senate that Tehran has “hosted” the terror group.

Did Iran collude with or harbor al-Qaeda?

Accusations of collusion with al-Qaeda have been leveled against Iran by U.S. officials since the Bush Administration. However, no concrete links between Iran and al-Qaeda related to the 9/11 attacks or the subsequent global War on Terror have yet been discovered.

The 9/11 Commission, tasked by the U.S. Government with investigating the attacks did find that Iran supplied explosives training to al-Qaeda operatives in the early 1990s and some al-Qaeda agents used Iran as a transit point during that period. However, the Commission made clear that they found no evidence that Iran was aware of or involved in the planning or execution of the 9/11 attacks. They note that although Iran did demonstrate interest in cooperating further with al-Qaeda during the 1990s, it was rebuffed by al-Qaeda’s leader Osama bin Laden who feared alienating parts of his membership and support base.

It should be noted that despite mutual antipathy towards the United States, al-Qaeda and Iran have little in common. Whereas al-Qaeda follows a strict interpretation of the Sunni branch of Islam, Iran’s is a Shi’a theocracy. These two Islamic sects have a history of conflict and theological disagreement going back more than 1000 years, and Sunni fundamentalists regard Shiites as heretics.  Furthermore, whereas al-Qaeda is a predominantly Arab organization, Iran is predominantly an ethnically Persian country where ethnic Arabs and Sunni Muslims face persecution and discrimination.

These religious fractures are evident in documents seized by U.S. officials in 2011 from bin Laden’s compound in Pakistan. They reveal that al-Qaeda’s leaders held deep mistrust and animosity towards Iran. Although they admit to often smuggling money and personnel through Iranian territory, they stress the importance of keeping such activities secret, as Iranian authorities had reportedly arrested or detained al-Qaeda operatives caught in the country as well as their families. Thomas Joscelyn, a Senior Fellow at the Foundation for Defense of Democracies, adds that the documents also show that bin Laden deplored Iran’s growing political influence in the Middle East.

Experts have also contradicted the Trump Administration’s allegations of Iran/al-Qaeda collusion. James Dobbins, who served as U.S. envoy to Afghanistan during the Bush Administration says that he does not believe that there “was ever any evidence [al-Qaeda] received active collaboration or support from Iran” after 9/11. Seth Jones, a former senior official in U.S. Special Operations Command argues that Iran has not harbored any active al-Qaeda agents and that the number of al-Qaeda members in Iran is likely “less than five.”

Moreover, divides reportedly exist within the Trump Administration over claims of Iran/al-Qaeda collusion. Rep. Matt Gaetz (R-FL), generally a fervent ally of President Trump, says that some Trump Administration officials, who wished to remain anonymous, have informed him that they also have found no evidence of Iran/al-Qaeda collusion despite claims made the President and Secretary of State. Senior U.S. Defense Department officials, including the Deputy Assistant Defense Secretary for the Middle East, have also denied finding or reporting any connections between Iran and al-Qaeda.

In fact, in 2001, Iran had offered military support to U.S. and Afghan forces in their mission to oust the al-Qaeda’s Taliban hosts from power. Moreover, Iran and al-Qaeda are currently active combatants on opposing sides in several ongoing Middle East conflicts, most notably the Syrian and Yemeni civil wars.

Could President Trump still invoke the AUMF for strikes on Iran?

A bipartisan group of lawmakers in both Congressional houses have expressed skepticism towards the Trump Administration’s claims of a post-9/11 Iran/al-Qaeda relationship. However, despite this and the lack of evidence, President Trump may ultimately still be free to invoke the AUMF and strike Iran without further Congressional approval for two key reasons.

First, the AUMF permits the President to strike any nation or organization “he determines” was involved in the 9/11 attacks. The text of the law includes no requirement that the President present any evidence for his determination or that Congress has to agree with it.

Furthermore, despite statements of concern over the law’s scope and application from individual members, Congress as a whole has since 9/11 proved unwilling to curtail the President’s power to wage war. Attempts to repeal the AUMF in 2016 and 2017 failed, and a measure which would require President Trump to seek a new Congressional authorization for any strikes on Iran was defeated in the Senate Foreign Relations Committee in May 2019, and again before the full Senate a month later.

The House of Representatives did pass a bill repealing the AUMF altogether in June 2019 however, analysts do not expect the measure to pass the Senate. President Trump’s Republican Party holds a majority in the Senate and, with the notable exceptions of Rep. Gaetz and Sen. Rand Paul (R-KY), most Republicans have opposed measures altering the AUMF. Senate Majority Leader Mitch McConnell (R-KY) has maintained that repealing the authorization would be “irresponsible” as it would cause “uncertainty” for currently deployed U.S. and allied forces about the future of their operations. 

Other bills limiting the AUMF have been introduced in both houses of Congress, however passing them may be a near-impossible task. Aside from Republicans’ hitherto opposition to this course of action, any such bill would likely have to pass with a two-thirds supermajority in both houses to survive a likely presidential veto.

Future Outlook

Their prior actions suggest that regardless of whether Iran meets the criteria set forth in the 2001 AUMF, if President Trump does choose to invoke it to strike Iran unilaterally, Congress will most likely decline to mount any meaningful opposition. As Rep. Lee and others have said over the decades, the AUMF essentially gives the President a “blank check” to begin new military operations so long as some connection to 9/11 or al-Qaeda can be drawn.

Several 2020 Democratic presidential candidates including, Mayor Pete Buttigieg, Rep. Tim Ryan (D-OH), Sen. Bernie Sanders (I-VT), Sen. Elizabeth Warren (D-MA), Sen. Kamala Harris (D-CA), Sen. Amy Klobuchar (D-MN), Sen. Kirsten Gillibrand (D-NY), Sen. Cory Booker (D-NJ) and Sen. Michael Bennet (D-CO), have all either issued statements or co-sponsored legislation which would either repeal the AUMF or require the President to obtain Congressional approval before striking Iran.

If one of these candidates is elected President, perhaps they will push for repeal of the 2001 AUMF, or unilaterally opt to not to begin or continue U.S. military deployments without seeking new Congressional approval. However, as Sen. Rand Paul argues, “every president” ultimately ends up arguing that “Congress can't tell them what to do on foreign policy or war.”