U.S. Strikes on Iran: A Long History of Military Action Without Prior Congressional Approval

Legal precedent supports President Trump's position

• The U.S. has not formally declared war since World War II, yet it has engaged in countless military operations, and even war, without prior congressional approval.

• From Trump’s first-term hits on the Islamic extremist terrorist group ISIS that grew to power under Obama, to Biden’s retaliatory strikes in Syria, the U.S. has frequently relied on expansive interpretations of executive authority to justify unilateral action.

• Legal precedent supports President Trump’s position.

The U.S. airstrikes on Iran’s nuclear facilities are igniting a firestorm of debate over presidential war powers, with critics arguing that President Trump’s decision to act without prior congressional approval violates the Constitution.

The strikes, targeting sites like Iran’s heavily fortified Fordo nuclear facility, follow a pattern of U.S. military actions abroad that sidestep Congress, a practice spanning decades.

But the high-stakes nature of bombing Iran—a regional powerhouse with the potential for devastating retaliation—has brought renewed scrutiny to this contentious issue.

Why do these strikes spark such outrage when unilateral action is so common? And what does history tell us about America’s approach to war powers?

Read on for details.

The Iran Strikes

B-2 stealth bombers in coordination with Israeli forces, struck Iranian nuclear sites, including Fordo, a deeply buried facility central to Iran’s nuclear program. The operation is part of a broader campaign following Israel’s initial strikes on June 13, aimed to cripple Iran’s nuclear ambitions amid stalled diplomatic talks and reports of Iran nearing critical and dangerous weapons-grade uranium enrichment.

The U.S. strikes, like so many before them, were conducted without prior congressional authorization. But they prompted fierce criticism, including from some of Trump’s fellow Republicans.

Democrats like Rep. Alexandria Ocasio-Cortez and House Minority Leader Hakeem Jeffries labeled the action unconstitutional, with some even raising the specter of impeachment.

Some progressive lawmakers were joined by libertarian-leaning Republicans like Rep. Thomas Massie (R-KY) in arguing that targeting a sovereign nation with advanced military capabilities crosses a constitutional threshold.

“This isn’t a drone strike on a terrorist camp,” said Sen. Tim Kaine (D-VA). “This is an act of war against a state that can hit back hard. Congress must have a say.”

Critics point to Article I, Section 8 of the Constitution, which grants Congress the power to declare war, and the War Powers Resolution of 1973, which requires presidential notification within 48 hours of military action and withdrawal within 60 days unless Congress approves.

They argue that the scale of the Iran strikes—targeting critical infrastructure with risks of retaliation against 40,000 U.S. troops in the region—demands congressional oversight.

Iran’s deputy foreign minister warned of a “quagmire,” citing Iran’s missile arsenal, cyber capabilities, and proxy militias like Hezbollah and the Houthis.

The Trump administration is defending the strikes as a “one-shot deal” to prevent a nuclear-armed Iran, relying on Article II powers, which designate the president as Commander-in-Chief, and claiming the action falls short of “war” in the constitutional sense.

Supporters of the U.S. action, like Rep. Mike Lawler (R-NY), cite historical precedents. They argue that presidents have long acted unilaterally to protect national security.

The Office of Legal Counsel (OLC), a key player in shaping executive action, has consistently argued that limited strikes don’t require congressional approval unless they involve prolonged, large-scale engagements.

Yet many say the Iran strikes stand out due to their potential for escalation.

Unlike operations against non-state actors like ISIS, targeting Iran risks a regional war, with analysts warning of “unknown unknowns” like cyberattacks or missile barrages on U.S. bases like Al-Asad in Iraq or Al-Udeid in Qatar. This context fuels demands for checks on presidential power, even as history shows such unilateral actions are far from new.

A Pattern of Unilateral Action: Historical Context

The U.S. has not formally declared war since World War II, yet it has engaged in countless military operations without prior congressional approval.

Presidents have relied on Article II, existing Authorizations for Use of Military Force (AUMFs) from 2001 and 2002 (the latter repealed in 2023), and flexible interpretations of the War Powers Resolution. The OLC often justifies these actions by defining “war” narrowly—excluding limited strikes or operations with low risk to U.S. personnel.

Below is a detailed list of notable U.S. strikes and operations that took place without pre-authorization.

Trump’s First Term (2017–2021): ISIS and Beyond

Trump’s first term saw an aggressive expansion of counterterrorism operations, particularly against ISIS, and several high-profile strikes, all conducted without prior congressional approval.

• Syria Airstrikes (April 2017):

  • Details: Trump ordered 59 Tomahawk cruise missiles against Shayrat Airbase in response to a chemical weapons attack by the Assad regime that killed over 80 civilians.

  • Justification: Article II powers to uphold international norms (such as Chemical Weapons Convention). Congress was notified but not consulted.

  • Reaction: Critics like Sen. Mike Lee (R-UT) and Rep. Thomas Massie (R-KY) argued it violated Article I, while supporters like Sen. Marco Rubio (R-FL) praised the action.

• Syria Airstrikes (April 2018):

  • Details: Over 100 missiles, launched with UK and France, targeted Syrian chemical weapons facilities after another suspected chemical attack.

  • Justification: Article II to enforce international norms. The 2001 AUMF was not cited, as the target was the Syrian government.

  • Reaction: Similar criticism for lack of authorization, but no legislative challenge materialized.

• ISIS Campaign in Iraq and Syria (2017–2021):

  • Details: Thousands of airstrikes targeted ISIS during battles for Mosul (2017) and Raqqa (2017–2018), supporting local forces like the Syrian Democratic Forces (SDF). Trump intensified operations compared to Obama.

  • Justification: The 2001 AUMF, covering “associated forces” of al-Qaeda, was stretched to include ISIS.

  • Reaction: Broad support for defeating ISIS, but Sen. Tim Kaine (D-VA) criticized the AUMF’s overuse.

• Soleimani Strike (Iraq, January 2020):

  • Details: A drone strike in Baghdad killed Iranian General Qasem Soleimani and Iraqi militia leader Abu Mahdi al-Muhandis, escalating tensions with Iran.

  • Justification: Article II (self-defense against imminent threats) and the 2002 AUMF (protecting U.S. forces in Iraq).

  • Reaction: Democrats like Rep. Ro Khanna (D-CA) called it unconstitutional, fearing war with Iran. Congress passed a non-binding resolution to limit Trump’s Iran actions, but it was symbolic.

• MOAB Strike (Afghanistan, April 2017):

  • Details: The U.S. dropped the “Mother of All Bombs” (MOAB) on an ISIS-Khorasan cave complex in Nangarhar, killing dozens of militants.

  • Justification: The 2001 AUMF and Article II (protecting U.S. forces).

  • Reaction: Minimal pushback, as the strike was seen as a tactical success.

• Yemen Drone Strikes and Raids (2017–2021):

  • Details: Trump expanded strikes against al-Qaeda in the Arabian Peninsula (AQAP). A 2017 raid in Al Bayda Province killed civilians, including a U.S. citizen child.

  • Justification: The 2001 AUMF and Article II (counterterrorism).

  • Reaction: The raid drew criticism for civilian deaths, but drone strikes were routine.

• Somalia Drone Strikes (2017–2021):

  • Details: Trump increased strikes against al-Shabaab and ISIS, relaxing Obama-era rules to give commanders more autonomy.

  • Justification: The 2001 AUMF and Article II.

  • Reaction: Limited scrutiny due to the low-profile nature of Somalia operations.

Biden’s Term (2021–2025): Retaliation and Counterterrorism

Biden’s administration continued unilateral strikes, often in response to attacks on U.S. forces, relying on Article II and the 2001 AUMF.

• Syria Airstrikes (February 2021):

  • Details: Strikes on Iranian-backed militia sites near the Iraq-Syria border, targeting Kata’ib Hezbollah after rocket attacks on U.S. bases in Iraq.

  • Justification: Article II (self-defense) and the 2002 AUMF.

  • Reaction: Critics like Rep. Ro Khanna (D-CA) called it unconstitutional. Syria condemned the violation of its sovereignty.

• Iraq and Syria Strikes (June 2021):

  • Details: Airstrikes hit Iranian-backed militia facilities after drone attacks on U.S. forces in Iraq.

  • Justification: Article II and the 2002 AUMF. Congress was notified per the War Powers Resolution.

  • Reaction: Progressive Democrats like Rep. Pramila Jayapal criticized the lack of authorization.

• Yemen Airstrikes (January 2024):

  • Details: U.S.-UK strikes on Houthi targets in Yemen, hitting over a dozen sites in response to Houthi attacks on Red Sea shipping.

  • Justification: Article II (defending international navigation). No AUMF was cited.

  • Reaction: Lawmakers like Sen. Mike Lee (R-UT) argued the strikes required authorization due to their offensive nature.

• Iraq and Syria Strikes (February 2024):

  • Details: Over 85 strikes on Iranian-backed militias and IRGC sites after a drone attack in Jordan killed three U.S. service members.

  • Justification: Article II and the 2002 AUMF.

  • Reaction: Critics demanded a new AUMF, and Iraq protested violations of its sovereignty.

• Somalia Airstrikes (2021–2025):

  • Details: Continued strikes against al-Shabaab and ISIS, including a 2023 strike killing ISIS leader Bilal al-Sudani.

  • Justification: The 2001 AUMF and Article II.

  • Reaction: Minimal, as these were routine counterterrorism operations.

• Afghanistan Drone Strike (August 2021):

  • Details: A Kabul strike targeting a suspected ISIS-K bomber killed 10 civilians, including seven children, during the U.S. withdrawal.

  • Justification: The 2001 AUMF and Article II.

  • Reaction: Widespread criticism for civilian casualties, but no challenge to the lack of authorization.

Historical Precedents

The practice predates Trump and Biden, with presidents exploiting legal ambiguities to act unilaterally.

• Grenada Invasion (1983, Reagan):

  • Details: U.S. invaded to oust a Marxist government and protect citizens.

  • Justification: Article II (protecting Americans).

  • Reaction: Mixed; some supported, others criticized bypassing Congress.

• Panama Invasion (1989, Bush Sr.):

  • Details: U.S. invaded to remove Manuel Noriega.

  • Justification: Article II (combating drug trafficking and protecting U.S. interests).

  • Reaction: Limited pushback due to success.

• Somalia and Bosnia (1990s, Clinton):

  • Details: Airstrikes and peacekeeping under UN mandates.

  • Justification: Article II and international obligations.

  • Reaction: Debates over authorization, but no significant congressional action.

• Libya Airstrikes (2011, Obama):

  • Details: NATO-led airstrikes to protect civilians during the Libyan civil war.

  • Justification: Article II and UN Security Council resolutions. Obama argued it wasn’t “war” due to limited U.S. involvement.

  • Reaction: Critics like Rep. Justin Amash (R-MI) called it unconstitutional, but Congress didn’t force withdrawal.

The U.S.-Afghanistan War: A Special Case

The Afghanistan War (2001–2021), the longest war in U.S. history, was initiated without prior congressional authorization in the form of a formal declaration of war, though it was supported by the 2001 Authorization for Use of Military Force (AUMF).

Following the 9/11 Islamic extremist terrorist attacks on the U.S., President George W. Bush launched Operation Enduring Freedom on October 7, 2001, targeting Islamic extremist al-Qaeda and the terrorist Taliban in Afghanistan.

The 2001 AUMF, passed by Congress on September 14, 2001, authorized the president to use force against those responsible for 9/11 and associated forces, providing a broad legal basis for the invasion.

However, critics, including legal scholars like Oona Hathaway, argue that the AUMF was not a specific authorization for a decades-long war, as it lacked defined scope or time limits, and its use to justify prolonged operations against evolving threats stretched constitutional intent.

The absence of a formal war declaration, combined with the war’s expansion into a nation-building effort, fueled debates over executive overreach, with Congress never fully reasserting its Article I war powers despite the conflict’s massive cost and duration.

Why the Outcry Over Iran?

The Iran strikes differ from past actions due to their stakes. Unlike strikes on non-state actors like ISIS or weaker states like Syria, Iran is a formidable adversary with advanced military capabilities. The risk of escalation—potentially involving missile attacks on U.S. bases or allies like Israel—amplifies calls for congressional oversight. The repealed 2002 AUMF and the 2001 AUMF’s questionable applicability to Iran leave a legal gap, strengthening arguments that Trump needed authorization. Public war fatigue, fueled by missteps in Iraq and Afghanistan, further drives skepticism, with fears of another prolonged conflict.

Yet historical precedent favors Trump’s legal position. Presidents have long exploited the OLC’s narrow definition of “war” and Congress’s reluctance to enforce the War Powers Resolution. The debate over Iran reflects not just legal concerns but also political divisions and fears of a regional quagmire.

What’s Next?

As Iran vows retaliation and lawmakers push resolutions to curb Trump’s authority, the strikes highlight a persistent tension in U.S. governance: the balance between executive agility and democratic accountability.

Will Congress finally assert its war powers, or will the pattern of unilateral action continue? For now, the world watches as the fallout from Fordo unfolds, a stark reminder of America’s complex relationship with military power.