War Powers in Real Time: What Happens If Congress Pushes Back During Active Combat?

U.S. military forces are once again engaged in hostilities involving Iran — what President Trump has described as “major combat operations.” Early indications suggest the administration is proceeding under Article II constitutional authority, consistent with prior executive practice, and subject to the reporting requirements of the War Powers Resolution.

That initial phase, however, is only part of the constitutional equation. In a hyper-polarized political environment, the more difficult question may come next: What happens if Congress asserts its Article I authority — whether by declining authorization, directing withdrawal, or restricting funding — while U.S. forces are already engaged?

The U.S. Constitution deliberately divides war authority. Article I grants Congress the power to declare war and to raise and fund armed forces. Article II designates the President as Commander in Chief. That separation was not accidental. The framers intended friction in the decision to wage sustained war. Military force could be used, but prolonged hostilities were meant to carry legislative accountability.

Over time, however, the balance has shifted in practice. Presidents of both parties have relied on Article II authority to conduct limited strikes or short-term military operations without a formal declaration of war. The War Powers Resolution of 1973 was Congress’s attempt to impose procedural guardrails, requiring notification within 48 hours and setting time limits absent authorization. Yet it did not eliminate the gray zone between limited executive action and sustained conflict. In many instances, Congress has also preferred strategic ambiguity — allowing operations to proceed without forcing politically consequential war votes that would clearly define responsibility.

If Congress chose to assert its authority while hostilities are underway, several avenues exist. It could decline to pass an authorization for continued operations. It could pass a joint resolution directing the withdrawal of forces. Most significantly, it could restrict or refuse appropriations for operations related to the conflict. Under Article I, the power of the purse remains Congress’s most direct tool for shaping or halting military engagement.

Those mechanisms are constitutionally legitimate. The more difficult question is what their exercise looks like in real time, once forces are deployed and operational cycles are in motion.

Military operations do not pause while domestic political debates unfold. Funding restrictions or mandated withdrawal during active combat could disrupt logistics chains, intelligence and surveillance coverage, rotational schedules, and coalition coordination. Even absent immediate battlefield effects, public congressional division during a live operation would be observed closely by adversaries calculating risk and by allies assessing reliability.

That does not mean congressional oversight should disappear in the name of deterrence. It does mean the timing and manner of legislative intervention carry second- and third-order effects. A visible fracture between branches of government during hostilities can alter adversary perceptions, potentially encouraging escalation, asymmetric testing, or regional probing.

At the same time, congressional restraint carries its own risks. If sustained hostilities proceed without clear authorization, the gradual expansion of executive war-making authority becomes normalized. Over time, that drift can erode the structural balance the Constitution was designed to preserve. The absence of friction may offer short-term operational clarity, but it can weaken legislative accountability and blur the distinction between limited action and open-ended conflict.

The framers anticipated this tension. They placed the power to declare war and to fund military forces in Congress not to undermine national defense, but to ensure that sustained war would carry collective political responsibility. If Congress declines to exercise those authorities when significant hostilities are underway, it implicitly cedes ground in the constitutional framework.

This tension is not new. Congress restricted funding during the latter stages of the Vietnam War, effectively curtailing sustained operations. In 2011, the Obama administration faced bipartisan criticism over the Libya intervention and the limits of the War Powers Resolution. Presidents of both parties have conducted limited strikes in Syria and elsewhere under Article II authority without formal declarations of war. Each episode reflected the same structural friction: executive initiative tested against legislative responsibility.