President Donald Trump may consider deploying active-duty Marines or Army units to Chicago following a Supreme Court ruling that temporarily blocked his use of the Illinois National Guard, escalating a legal and political battle over federal authority, immigration enforcement, and public safety in sanctuary cities.

The issue stems from President Trump’s October 2025 decision to activate approximately 300 Illinois National Guard members for federal protection duties in Chicago. The deployment was intended to safeguard federal buildings and Immigration and Customs Enforcement agents amid growing threats tied to the city’s sanctuary policies. Illinois Governor J.B. Pritzker immediately challenged the move, calling it an unlawful overreach of presidential authority.

On December 23, the Supreme Court issued a 6–3 emergency ruling upholding a lower court stay, preventing the Guard’s deployment for now. The majority cited unresolved legal questions regarding whether “regular forces” must be used first under the Insurrection Act before federalizing state National Guard units. The decision did not rule against Trump’s authority outright but left the matter legally unsettled.

Fox News legal analysts noted that the ruling may actually open a different path forward for the administration. Under Title 10 of the U.S. Code, the president has clear authority to deploy active-duty forces, including Marines or Army units, to protect federal personnel and property without first involving the National Guard. Such deployments have historical precedent, particularly when states resist federal enforcement actions.

The analysis suggests that deploying active-duty troops could bypass the legal complications raised by Illinois officials and reinforced by the Court’s procedural ruling. Marines or Army units could be tasked strictly with defensive roles, such as guarding federal buildings and ensuring the safety of ICE agents, rather than engaging in local law enforcement.

Supporters of the president argue that sanctuary city policies have created dangerous conditions for federal officers tasked with enforcing immigration law, leaving the administration with little choice but to act decisively. They view the Supreme Court decision not as a defeat, but as a clarification that may strengthen the president’s hand moving forward.

Critics, including Democratic leaders, warn that the use of active-duty troops would further inflame tensions and set a troubling precedent. The Trump administration, however, has consistently maintained that protecting federal agents and upholding the rule of law is not optional — especially when state and local governments refuse to cooperate.

As legal challenges continue and threats against federal personnel persist, the possibility of Marines deploying to Chicago underscores the broader conflict between the Trump administration’s America First enforcement agenda and Democratic-led resistance at the state level. The coming weeks may determine whether the president chooses to exercise his full constitutional authority to ensure federal law is carried out.