In a dramatic escalation of military presence in Los Angeles, President Donald Trump ordered approximately 700 Marines to the city on June 9, 2025. The move was described by Secretary of Defense Pete Hegseth as a response to “increased threats to federal law enforcement officers and federal buildings.”
This deployment follows Trump’s June 7 directive that sent about 2,000 National Guard troops to Los Angeles, aimed at countering what he termed “numerous incidents of violence and disorder” from protestors opposing his administration’s immigration policies.
Local and state officials were quick to decry Trump’s actions. California Governor Gavin Newsom characterized the maneuvers as “purposefully inflammatory” and an “illegal act.” On the same day as the troop deployment, California initiated legal action against the Trump administration to halt the deployment of National Guard members. Critics of the actions contended that the scale and nature of the protests did not justify such extreme military measures.
To shed light on the president’s authority to deploy American troops within the country, Amy Lieberman, a politics and society editor at The Conversation U.S., consulted William C. Banks, an expert on the military’s role in domestic affairs.
The question of whether American troops can be utilized domestically brings to light a complex aspect of U.S. law. While it is within the president’s authority to deploy troops within the country, doing so is an extraordinary exercise of power that has been exercised sparingly in American history, particularly in response to civil disturbances.
The delegation of authority for domestic troop deployment is primarily outlined by Congress, permitting the president to use such power in limited circumstances. In other cases, authority rests with state governors, who maintain control over the National Guard.
The cautious approach towards military deployment in domestic affairs can be traced back to the founding of the United States, reacting against the oppressive military actions of King George III prior to the American Revolution. To prevent the misuse of military power by the government, the framers of the Constitution included provisions to create hurdles against the use of troops in American communities.
One such safeguard was ensuring the commander-in-chief of the military remained a civilian. Additionally, the authority to call up the National Guard—previously noted as the “militia”—was vested in Congress instead of the president, enhancing separation of powers.
Under the Insurrection Act of 1807, the president may deploy troops during what is classified as insurrection, which effectively refers to periods of significant civil unrest. The president must determine whether it is “impracticable” to enforce U.S. laws in a specific city and, depending on that evaluation, may mobilize military or National Guard forces to aid in restoring order.
To exercise this power, the president is required to issue a proclamation urging those designated as insurrectionists to cease their activities. If the individuals do not comply, the president can send in forces to intervene.
Although Trump has labeled the Los Angeles protesters as “insurrectionists,” he has not made a formal proclamation to that effect as of this writing. When he summoned California’s National Guard troops on June 7, it was for a narrowly defined purpose related to protecting federal properties and personnel involved in immigration enforcement.
The Posse Comitatus Act of 1878 further complicates any potential military involvement in domestic law enforcement. This legislation establishes a presumption that the military should refrain from participating in domestic law enforcement duties unless specified exceptions are applicable, such as the Insurrection Act.
Enforced by this act, the military and National Guard are trained to avoid engaging in legal enforcement roles typically reserved for civilian police forces. Thus, under the Insurrection Act, military forces would have the capacity to operate as law enforcement—conducting arrests, investigations, and detaining civilians—while remaining subject only to constitutional limitations.
This scenario presents a challenge for California’s National Guard, trained mainly for disaster response such as wildfires, rather than civil unrest management.
Legal experts indicate that there are no significant legal roadblocks that could effectively limit the president’s power to send troops into Los Angeles. Furthermore, state governors or other elected officials do not possess the legal authority to prevent the deployment of U.S. troops in their jurisdictions.
The unfolding situation in Los Angeles raises significant questions not only about presidential power but also about the long-standing principles of civil liberties and the appropriate role of military forces in domestic affairs.
image source from：https://theconversation.com/trump-orders-marines-to-los-angeles-as-protests-escalate-over-immigration-raids-demonstrating-the-presidents-power-to-deploy-troops-on-us-soil-258527
