During his State of the Union address, President Donald Trump reaffirmed his orders to deploy “another 3,750 troops to our southern border” to prepare for a “tremendous onslaught” of migrants seeking to illegally cross into the United States. Trump’s language drew boos from some members of the lower chamber. However, these are boos of irony. The same members of Congress booing the president, decrying his use of executive authority, are the very legislators with the power to restrict it. Now that a congressional spending bill has been passed—but not with the specific border wall funding provisions sought—President Trump is using his executive authority to “declare a national emergency” at the border. With Congress not meeting the administration’s demands, such an emergency will formally permit the president to deploy even more resources to the border.

Congressional ignorance (or apathy) is precisely why the United States has morphed the military into a new twenty-first-century national security architecture in which everything can be an existential threat. Rosa Brooks astutely identified this growing issue in How Everything Became War and the Military Became Everything, where she described how the US military is becoming an “all-purpose tool” for problems around the world. The same trend, it appears, holds true for problems at home.

The American defense enterprise has modernized and adapted to fit changing times. Unfortunately, US defense policy and law governing the domestic use of the military lags. It only took one president motivated by partisan gridlock and a bedrock campaign promise to challenge tradition and buck the status quo. Unless Congress acts to bring modern American defense policies and laws into the twenty-first century, things like the use of executive orders to identify an existential threat by presidential decree will only continue. This is problematic because the use of executive orders to address national security problems is a new form of norm erosion, especially when Congress is fully capable of passing legislation to address threats to US security. For instance, Congress actually passed legislation regarding Chinese political operations in the United States, and appears primed to pass even more legislation to deal with Chinese espionage, to include even restricting Chinese students and their access, due to some of these students passing sensitive information and technology to Chinese intelligence.

However, Congress is not fully to blame. Annoyed by congressional inaction, President Trump has issued more executive orders—on average, per year—than every president since Jimmy Carter. Overreliance on executive orders can establish new norms of presidential conduct that skirt the normal democratic process. Norm erosion in presidential behavior is not a new phenomenon per se. President Franklin D. Roosevelt was the first president to serve more than two terms, breaking with tradition that was first established by George Washington. Several years later, Congress would eventually pass the Twenty-Second Amendment, formally restricting presidents to two terms, as a response to Roosevelt’s breaking of the presidential tradition. The degradation of presidential norms becomes insidious, though, when a supposed national security threat can be declared a national emergency without any check on this power.

Following a newly established precedent, future presidents may continue leveraging the full extent of executive authority in their use of the military to address virtually any “threat.” Under the current national security architecture this is completely legal. Senator Marco Rubio recently described the slippery slope of over-securitizing threats, stating, “If today the national emergency is border security, tomorrow the national emergency might be climate change.” This is already within the realm of possibility given that a 2014 Department of Defense report noted that climate change is a future trend “that will impact our national security.”

A Crisis or Not?

The president’s use of active-duty troops on the US southern border is entirely legal—despite contradictory public narratives—and within the scope of the executive authorities bestowed on the president. The issue is not that President Trump is breaking laws in his use of the military on the border; rather, he is leveraging executive authority more than any president in the post–Cold War era to accomplish his intent, albeit in a way inconsistent with tradition. It is the departure from established norms and values in his use of the military, not a violation of law, which draws attention. The fact is, the twenty-first-century national security architecture begs modernization. Dated vestiges of defense policy and law, rooted mostly in nineteenth-century tradition and precedent, still influence the application of military power today.

Until 2016, constitutional relics such as the 1878 Posse Comitatus Act and the 1807 Insurrection Act laid in hide, rarely stepping into the mainstream narrative. For hundreds of years, US presidents followed normative traditions in their use of the military on domestic soil, reserving domestic military troop deployments for the most dire of circumstances.

Owing to the Posse Comitatus Act, presidents generally resisted deploying active-duty forces within the United States and adhered to past precedent (e.g., allowing governors to mobilize guard units). For instance, the perceived slow response of the US military to major riots and natural disasters is more a product of bureaucratic norms and legalistic hurdles than a lack of American military readiness to mobilize and respond. Norms of restraint, if you will, established a seldom-use paradigm for the military domestically, essentially codifying it into unwritten tradition of presidential behavior. But tradition alone provides insufficient grounds for deterring a particularly motivated president intent on delivering on a campaign promise.

Despite the availability of legal yet seldom-used authorities to bypass Posse Comitatus Act restrictions and deploy troops domestically, past presidents rarely invoked them. For example, since 1952 there have only been twelve incidents (excluding overseas contingency support) of a president mobilizing the National Guard under federal authority to respond to a serious domestic event. Compared to federalizing the National Guard, deployments of federal troops under an invocation of the Insurrection Act were even rarer in the twentieth century. The 1992 Los Angeles riots were the last time that the Insurrection Act was formally invoked. Even then, federal troops deployed to the Los Angeles area remained in a behind-the-scenes support role and did not participate in the suppression of violence. Despite considerations of invoking the Insurrection Act immediately after 9/11 and then again in the wake of Hurricane Katrina, President George W. Bush resisted. To date, no such invocation of the Insurrection Act or federalization of the National Guard for domestic response has occurred in the twenty-first century.

In his first two years in office, President Trump has, repeatedly, threatened to “send in the Feds,” a certain indication of his willingness to use federal resources—like the military—to deal with local and state problems. The perceived porosity of the US southern border and the president’s fervent campaign promise to secure it have only furthered this rhetoric. In the early stages of the Trump presidency, most critics, the media, and members of Congress dismissed these comments as improbable, impractical, and impermissible. As the border security issue generated greater media attention in mid- to late 2018, and as the president’s narrative expanded, the same critics, media personalities, and members of Congress started to pay more attention.

What was once considered improbable, impractical, and impermissible has quickly risen to the precipice of probable and permissible (if still not all that practical, depending on one’s perspective). President Trump’s insistence on securing the southern border and the continued fight to secure funding for a border wall may present the first such invocation of the Insurrection Act or federal domestic mobilization of the National Guard this century. Absent legislative changes by Congress, it is within the purview of executive authority to bypass the restrictions of the Posse Comitatus Act and deploy troops within the United States. Yet, sections of the Insurrection Act alone are not the only authority the president can rely on to secure the border—or anything else a president might deem an existential threat.

With border security funding battles raging in Congress, President Trump now appears primed to declare a national emergency. Such declarations are traditionally reserved for existential crises when the power and capacity of local and state governments is overwhelmed or insufficient to deal with the situation at hand. The problem is that—unlike the constitutions of other Western countries, which specify the mechanics of emergency declarations—there are no constitutional provisions outlining the process, requirements, or qualifying circumstances for such a declaration in the United States. Per 50 US Code § 1631, the president can declare a national emergency by executive order, which “specifies the provisions of law under which he proposes that he, or other officers will act.”  In other words, the president can declare a national emergency at his discretion, and with few exceptions, can also determine which laws will be used to justify emergency action, albeit with substantial political risk. Given the relative ambiguity of numerous laws, presidential authority widens a great deal under such circumstances.

Such political risk has generally served as a sufficient deterrent to past presidents and ensured compliance with conventional norms of the office. However, the ambiguities of existing law and the absence of formal emergency powers legislation, ironically, create an unrestricted framework ripe for manipulation by a president willing to disregard those norms and accept the political risk. The lack of clearly defined legislative restrictions on emergency powers creates a threat in and of itself; a threat that, arguably, most elected officials have not in the past considered a likely scenario. This presents various dangers to civil-military relations, given that a president might theoretically choose not just to deploy troops to guard the border but, say, to send tanks and Apache helicopters to fight gang violence, all under the guise of a “national emergency.” Without laws in place restraining this, there is little left to the imagination of how the US military might legally be deployed in the future.

A Way Forward: Congress Needs a New, Twenty-First-Century National Security Architecture

The 9/11 attacks and subsequent Global War on Terrorism were critical junctures for civil-military relations. Set on this new path, there has been an erosion of anti-militarism principles that our Founding Fathers ascribed to, all because of threat inflation. It extends to the resulting militarization of traditionally non-military problems that Charles Dunlap warned us of in 1992 and Rosa Brooks again reminded us of in 2016. Critics of the president argue that treating the current border situation as a national crisis defies reality and empirics, as US border crossings are at their lowest in seven years. Others believe that this a real crisis presenting a legitimate threat to national sovereignty. For the president, a seven-year low in border crossings is only a relative value to the number of crossings that was already crisis seven years ago. In that context, anything above zero only contributes to the problem. Regardless of perspective, the central issue here is the president’s use of executive privilege to legally bypass normative checks and balances. The system has been largely stable because presidents have historically been concerned with their political futures and legacies, and thus unwilling to depart from tradition.

Expanded use of executive privilege, leveraging archaic laws for modern military force application, ballooning funding, and the rise of ad hoc military operations in the periphery have given way to a new defense paradigm. It is propelled by the inertia of a seemingly unstoppable system that has—in recent years—outpaced legislative revision. As a result, there is a rising challenge to normative civil-military relations in the twenty-first century. Congress can combat this disease by revising and modernizing the national security legal architecture, which would prevent America’s most trusted institution—the military—from being politicized.

New congressional legislation that checks and balances executive powers is a necessary precondition for the success of the US military in the twenty-first century. Threats to the US homeland and American military capabilities are vastly different now compared to the nineteenth century, which means much-needed reform is vital. Creating a Posse Comitatus Act version 2.0 is in order. Explicitly ascribing what the president can and cannot do with the military domestically would ensure that the military remains beyond the fray of politicized threat assessments.


Dr. Ryan Burke is an associate professor of Military & Strategic Studies at the U.S. Air Force Academy and is a former Marine Corps officer. He has written on the subject of military-involved domestic and international support for international journals; the Strategic Studies Institute; and others. He is also the chief editor of Military Strategy, Joint Operations, and Airpower: an Introduction (Georgetown University Press, 2018).

Jahara “Franky” Matisek is a Non-Resident Fellow at the Modern War Institute. He is an active duty officer in the US Air Force, currently serving as an Assistant Professor in the Department of Military and Strategic Studies at the US Air Force Academy. A former C-17 Pilot with over 2,000 hours of flight time, to include over 700 hours of combat time, he holds a PhD in Political Science from Northwestern University.

The views expressed are those of the authors and do not reflect the official position of the United States Military Academy, Department of the Army, Department of Defense, or any organization or institution with which the authors are affiliated.


Image credit: Robert Bushell, US Customs and Border Protection Office of Public Affairs