You need Congressional approval for war.
The primary reasons cited for President Trump not needing prior congressional approval for the U.S. military strikes on Iran (launched jointly with Israel around February 28, 2026, targeting nuclear facilities and related sites in what the administration called a limited operation) center on longstanding presidential authority, historical precedent, and the nature of the action.
Key arguments include:
• Presidential authority for “important national interests” in limited operations: The Justice Department’s Office of Legal Counsel (OLC) opinions across Democratic and Republican administrations (including Clinton, Obama, and Trump) have consistently held that the president can act unilaterally if the operation serves key U.S. interests and does not rise to the level of a full “war” (defined as prolonged, substantial engagements with high risk to U.S. forces over time). The Iran strikes were framed as targeted, limited-scope actions against nuclear sites (e.g., Fordow, Natanz, Isfahan), not an open-ended invasion. This mirrors precedents like Clinton’s 1995 Bosnia air campaign (over 2,300 sorties in two weeks) and Obama’s 2011 Libya operation (hundreds of missiles), both done without prior approval.
• War Powers Resolution (1973) permits initial action: This law requires the president to notify Congress within 48 hours (which the administration did via briefings to the “Gang of Eight” and committees) and allows up to 60 days of operations before needing approval (or withdrawal). Courts have shown deference to presidents on this “vague standard,” and the resolution is often viewed as an unconstitutional limit on executive power anyway. Congress can vote to restrict or end it later.
• No specific congressional prohibition + implicit support: Over 20+ years, Congress never passed laws barring force against Iran’s nuclear ambitions. In fact, the House passed a 2023 bipartisan resolution (354-53) stating it is U.S. policy to “use all means necessary” to prevent Iran from getting a nuclear weapon. Funding appropriations have also sustained such operations. If Congress opposed it strongly, it could have acted proactively (or can still pass new limits).
• Imminent self-defense and national security threats: Iran’s nuclear dash, proxy attacks (killing/maiming Americans via roadside bombs and more), and “Death to America” rhetoric created a direct threat. The strikes also supported collective self-defense for Israel under international law. Some also referenced the 2001 AUMF (still in effect and unrepealed) as potentially covering Iran as an al-Qaeda harborer.
• Decades of bipartisan precedent: Prior presidents (both parties) have conducted similar strikes without approval. Federal courts have largely stayed out, declining to block such actions.
In short, these sources view the strikes as a classic exercise of executive foreign policy and defense powers for a time-sensitive, non-“war” operation against a clear adversary—consistent with how U.S. presidents have operated for decades.
The Trump administration did inform (or attempt to inform) the Gang of Eight prior to the U.S.-Israeli strikes on Iran on February 28, 2026. 
According to multiple reports:
• White House Press Secretary Karoline Leavitt stated that Secretary of State Marco Rubio called all members of the Gang of Eight to provide congressional notification prior to the attacks. He reached and briefed seven of the eight members.

• House Speaker Mike Johnson (a member of the Gang of Eight) confirmed that the group was briefed in detail earlier in the week about the possibility of military action to protect U.S. troops and interests. He received updates from Secretary Rubio afterward. 
• Rubio reached out by phone and text shortly before the operation began, consistent with the administration’s approach to congressional notification under the War Powers Resolution (which requires notification within 48 hours of action, but here they provided advance heads-up to key leaders).