It was Pearl Harbor–level language. “America’s sovereignty is under attack,” Donald Trump proclaimed on day one of his return to the White House. The president’s cause for alarm? A “National emergency at the southern border,” as the administration labeled it, referring to a frontier that, for all intents and purposes, was comparatively quiet.
The same day, he called on the commanders of the US armed forces to prepare for potential domestic law enforcement. To that end, he asked that plans be drawn up to invoke, if necessary, a nearly 220-year-old “insurrection” law that would give him authority to send federal troops to crack down on the purported southern “invasion.” Later that week, the new secretary of defense, Pete Hegseth, said in his first remarks at the Pentagon that the military was ready to shift its priorities from possible overseas deployment and engagement to “the defense of the territorial integrity of the United States of America” in compliance with “the Constitution, the laws of our land and the directives of the commander.”
And this past weekend, President Trump and Governor Greg Abbott reached a deal to grant the Texas National Guard new authority to make immigration arrests as long as they were alongside immigration officers and border patrol agents. This was, in fact, a “legal action,” but one normally seen only in times of serious crises.
Such declarations and acts seemed chilling, yet specific: Trump’s and Hegseth’s decrees clearly targeted migrants seeking to destabilize the American homeland. Then again, maybe not. Indeed, some have begun to wonder if the president and secretary of defense are preparing for a more all-encompassing contingency: not only an armed bulwark against an already diminishing immigrant influx at the border, but also for a mobilization that could be utilized against political opponents who supposedly threaten the nation’s “territorial integrity”—with troops potentially marching into states and sanctuary cities, even schools and private homes, that resist deportation orders. This is, after all, the playbook of autocrats. Reminder: shaking free of such ironclad bonds to executive and military authority is why the colonies rebelled against the British in the first place.
What might the president be up to? What are the precedents for invoking the Insurrection Act? And what are individual members of the American military doing to anticipate choices they may have to make in the weeks and months ahead?
Trump, it should be noted, flirted with invoking the Insurrection Act during his first administration. That law, which is an amalgamation of statutes enacted between 1792 and 1871, grants the president sole authority to send armed forces into rebellious states, even over the objections of their governments. During the civil unrest that followed the murder of George Floyd, on June 1, 2020, Trump warned, “If a city or state refuses to take the actions that are necessary to defend the life and property of their residents, then I will deploy the United States military and quickly solve the problem for them.” The New York Times noted at the time that Trump planned to announce he was ready to use his powers under the rarely invoked law to override governors and send active-duty troops to states where there were protests. Trump was reportedly dissuaded from such a declaration by senior White House and Pentagon officials.
But that same month, he did send troops into Washington, DC, the one place in the country where he would not face opposition from a governor. That was when peaceful demonstrators were forcefully cleared from Lafayette Square by US Park Police, National Guard members, and law enforcement officers from various federal agencies, including the Secret Service. On that occasion, Secretary of Defense Mark Esper, along with Mark Milley—the chairman of the Joint Chiefs of Staff, dressed in US Army fatigues—walked briefly together with Trump into the square, stopping at St. John’s Church, where the president posed for photographs while holding a Bible.
Shortly thereafter, a chagrined Milley issued an apology for agreeing to take part in such a display. “I should not have been there,” he stated during a commencement address at National Defense University, an educational center for top military and national security leadership in Washington, DC. “My presence in that moment and in that environment created a perception of the military involved in domestic politics. As a commissioned uniformed officer, it was a mistake that I have learned from, and I sincerely hope we all can learn from it.” Milley, now retired and recently granted a preemptive pardon by Joe Biden, still faces Trump’s wrath—including possible demotion in rank—for this and other statements and actions.
The Insurrection Act is murky. Part of the reason is that sending soldiers to do police work is inherently risky, even when seemingly justified. The last time the Insurrection Act was invoked was almost 33 years ago. In May 1992, George H.W. Bush summoned the Marines to help quell the Los Angeles riots that followed the acquittals of four officers charged with assault in the beating of Rodney King. Some 13,500 federal troops, including more than 10,000 from the California National Guard, accompanied the LAPD.
At one point, in the waning days of the unrest, seven marines went along with two local police officers responding to a domestic violence call. What was an ordinary situation for the cops was anything but for the soldiers, according to Joseph Nunn, a lawyer who works with the Liberty and National Security Program of the Brennan Center, an independent think tank. “These Marines now found themselves playing a role for which they had little training: that of civilian law enforcement officer,” he explains in a report on reforming the Insurrection Act. He describes the scene: someone inside the house fired a shotgun through the door. One of the officers shouted, “Cover me.” For the police, that meant: hold your weapons up in a position ready to fire, if necessary. “The Marines,” writes Nunn, “in accordance with their own training, took it as a request for suppressing fire. They riddled the home with more than 200 bullets. Miraculously, no one was killed.”
This is not to say that trained US soldiers are never deployed on American soil. Today, under normal legal precedent, the military is already actively working in support of law enforcement, with some 4,000 federal troops aiding border and Customs agents, though typically without power to arrest offenders. The Pentagon, meanwhile, operates military flights when apprehended immigrants are returned to their home nations. But these activities are different from direct, face-to-face engagement by uniformed military personnel in domestic law enforcement matters. To take that fateful step, Trump would have to invoke the Insurrection Act.
The first step down this path came on Inauguration Day. Trump’s emergency order set a 90-day deadline for the secretaries of defense and homeland security to have an action plan for obtaining “complete operational control of the southern border, including whether to invoke the Insurrection Act.”
Why would the president need such approval? Because of Congress’s checks and balances on a president’s executive power when it comes to using troops. The Constitution, in various ways, limits military involvement in civilian affairs. But it does not entirely bar federal armed forces from conducting law enforcement actions. Instead, a partial prohibition comes from the Posse Comitatus Act of 1878. In it, Congress expressly forbids federal armed forces from acting as police on the nation’s streets unless such action is authorized by Congress or the Constitution. But there’s one gaping loophole that comes into play only when the president, in a time of national or state emergency, unilaterally invokes the Insurrection Act. According to the Brennan Center: “The Insurrection Act allows the president—with or without the state government’s consent—to use the military to enforce federal law or suppress a rebellion against federal authority in a state.” Even if a state’s government objects, soldiers can, at the president’s behest, march in to stop insurrections and act as police.
