On June 21, 2023, President Donald Trump announced that U.S. warplanes had executed strikes on three Iranian nuclear facilities. This military action aligns with Israel’s ongoing efforts to neutralize what both nations perceive as a significant threat. Following the strikes, Trump addressed the nation to provide clarity on the situation and the rationale behind the military operations.
Trump's prior warnings regarding U.S. involvement in military action against Iran have raised critical concerns about the scope of presidential authority and the necessity of congressional approval for military operations abroad. In response, lawmakers from both the House and Senate introduced resolutions aimed at ensuring that Trump obtains congressional authorization before any U.S. military engagement against Iran can proceed.
What authority does the president hold to initiate such military strikes? The legality of President Trump’s actions under both U.S. domestic law and international law is a contentious topic. According to my testimony before the Senate Foreign Relations Committee in 2017, the president possesses broad powers under the Constitution to order military force. His Article II powers empower him to deploy military action not only for the defense of the United States against actual or anticipated threats but also to promote other significant national interests.
Historically, U.S. presidents from both major political parties have engaged military forces without seeking congressional authorization. Article I of the Constitution does grant Congress the authority to “declare War,” but this has not been interpreted to necessitate congressional approval for every military action initiated by the president.
The Department of Justice’s Office of Legal Counsel (OLC) has recognized that the "declare War" clause may impose limitations on the president’s Article II powers in scenarios that could escalate to a state of "war." The OLC has indicated that determining whether a military engagement qualifies as "war" necessitates a detailed analysis of the anticipated nature, scope, and duration of military operations. Typically, this standard applies to prolonged and significant military engagements that expose U.S. forces to considerable risk over time.
Applying these legal principles to a potential strike on Iran suggests that if military action is substantial and poses significant risks to U.S. personnel or interests, there is a compelling argument that it would require congressional approval, consistent with Congress' constitutional authority.
In past military operations, both Republican and Democratic presidents have generally sought congressional authorization for significant uses of military force. For instance, President George H.W. Bush successfully sought congressional backing for the Gulf War in 1991, while President George W. Bush obtained authorizations for military actions post-9/11 in 2001 and 2002 against those responsible for the attacks and Iraqi leader Saddam Hussein.
Legal experts argue that a U.S. military attack on Iran could contravene international law. The UN Charter and customary international law strictly limit the use of force against another nation, allowing it only in self-defense or with UN Security Council approval. The right to self-defense encompasses actions taken to mitigate imminent armed attacks. However, framing a strike against Iran’s nuclear facilities as self-defense against an imminent threat would be challenging.
The Trump administration might contend that any military action against Iran is justified as an act of collective self-defense for Israel. Yet, the legitimacy of such a claim would depend on whether Israel's initial actions against Iran were lawful and whether U.S. force is strictly aimed at safeguarding Israeli civilians and American interests from potential Iranian aggression.
In recent decades, Congress has increasingly accepted military actions undertaken by presidents without formal congressional consent or oversight. Although the president enjoys broad constitutional authority to protect U.S. interests, a military strike on Iran would represent a significant overreach of that power, carrying considerable risks for both U.S. military personnel and civilians.
If Congress is to play a meaningful role in matters of war powers, members from both parties must advocate for thorough consultation between the president and Congress prior to any military action against Iran. This collaborative approach is crucial to maintaining the balance of power as outlined in the U.S. Constitution.
