Trump Sends Troops to the Southern Border: A Crisis or a Continuation of U.S. Policy?

Photo: Scott Nelson/Getty Images
President Donald Trump sent U.S. troops to the southern border in one of his first actions as commander-in-chief. That he took such an action is not surprising since border security was the central theme of his campaign. Indeed, immigration actions constituted 8 of President Trump’s first 50 executive orders (EOs). The United States has had troops on the border for over 30 years. Unprecedented, however, is President Trump’s tasking the military with “sealing the border” and the potential scale of military involvement. These critical questions explore what President Trump has directed, what the forces might do, how effective they might be, and what the deployment’s effect will be on U.S. readiness for other emergencies.
Q1: What emergency powers has President Trump invoked?
A1: The EO Declaring a National Emergency at the Southern Border of the United States provides the rationale for emergency actions: “America’s sovereignty is under attack. Our southern border is overrun by cartels, criminal gangs, known terrorists, human traffickers, smugglers, unvetted military-age males from foreign adversaries, and illicit narcotics that harm Americans.” Other EOs use the term “invasion” to describe the situation.
Building on this rationale, the EO “declare[s] that a national emergency exists at the southern border of the United States, and that section 12302 of title 10, United States Code, is invoked and . . . that the construction authority provided in section 2808 of title 10, United States Code, is invoked and made available,”
This legalese needs unpacking.
- Section 12302 of Title 10, United States Code. This allows the president to call up reservists involuntarily. Although no activations have been announced yet, a large and extended military presence at the border might require involuntary reserve mobilization, especially to relieve active-duty forces. The authority allows up to 1,000,000 activations for 24 months, but historically, activations have been for about a year and only a few thousand at a time, except for the wars in Iraq and Afghanistan. President Trump used the authority in his first term for operations to counter Covid-19. President Biden used the authority twice: once for an exercise in Europe and another time to combat drug trafficking.
- Construction authority in section 2808 of Title 10, United States Code. This allows the Department of Defense (DOD) to “undertake military construction projects . . . not otherwise authorized by law that are necessary to support such use of the armed forces . . . [but] within the total amount of funds that have been appropriated for military construction.” With this authority, the administration will likely shift funds from other DOD construction projects to build more of the border wall. This requires canceling congressionally authorized projects to free up money. These canceled projects will likely appear in future budgets.
Q2: What has President Trump directed the military to do?
A2: Two executive orders affect the military the most. One directs the military to “seal the border,” and the other directs the deployment of troops to the southern border.
The EO Clarifying The Military’s Role In Protecting The Territorial Integrity Of The United States directed, “No later than 10 days from the effective date of this order, deliver to the President a revision to the Unified Command Plan that assigns United States Northern Command (USNORTHCOM) the mission to seal the borders and maintain the sovereignty, territorial integrity, and security of the United States by repelling forms of invasion including unlawful mass migration, narcotics trafficking, human smuggling and trafficking, and other criminal activities.” It also required from NORTHCOM “a commander’s estimate [for executing these tasks] due to the Secretary of Defense within 30 days.”
This commander’s estimate will specify how many troops are needed, for how long, and for what tasks. Given the broad scope of the task, the number could be very large.
The EO Securing Our Borders directed, “The Secretary of Defense and the Secretary of Homeland Security shall take all appropriate and lawful action to deploy sufficient personnel along the southern border of the United States to ensure complete operational control.”
Although the EOs did not specify numbers, the DOD announced that 1,500 troops were being sent to the southwest border immediately. Despite speculation about premier warfighting units like the 82nd Airborne Division being sent, all units announced so far are logistical and support. This adds to the 2,500 troops already there from the Biden administration and 18,000 Border Patrol (BP) members. A total of 10,000 troops has reportedly been discussed. Note, however, that this does not include any results from the NORTHCOM commander’s estimate.
Q3: What tasks will the troops do on the southern border?
A3: A “senior military official” described these actions: “We anticipate that overall, on the southwest border, [active-duty personnel] will provide real-time situational awareness of persons, vehicles, vessels, and aircraft; and they’ll work with [U.S. Customs and Border Protection (CBP)] on operator-level maintenance, movement, and staging of [CBP] assets,” In a separate statement, the acting secretary of defense said, “The Department will begin assisting in the construction of temporary and permanent physical barriers to adding additional security to curtail illegal border crossings and illicit trafficking.” The NORTHCOM website similarly lists support tasks: motor transport, minor construction, heavy equipment, detection, medical, and aviation support for BP.
Note that these are support tasks that do not involve direct contact with migrants (except for medical treatment). The Posse Comitatus Act prevents active-duty troops from conducting law enforcement activities, so they are limited to support functions as described by NORTHCOM. National Guard troops, when acting in a state role, are not subject to Posse Comitatus, but, by policy, their role is also limited. Mobilization rules for the National Guard are complex, covering both state activations (Title 32) and federal activations (Title 10). President Trump’s EO authority is for federal activation.
Q4: Can the troops really “seal the border”?
A4: No, sealing the border is impossible; the border is too long (1,950 miles), and the number of troops is too small. The image of troops lining up to repel illegal immigration is attractive but inaccurate, despite the rhetoric about invasion. If all the troops and BP personnel were lined up on the border, there would only be one every 150 yards.
However, reducing the flow of illegal immigrants is possible. The troops allow BP to strengthen the cordon and reduce the flow of illegal immigrants. The aim of border security is not to reduce the flow to zero because that is impossible. The aim is to reduce crossings to a manageable level by making crossing more difficult, thereby discouraging immigrants from trying to enter without documentation and interdicting more of those who still try.
Q5: Are these actions unusual?
A5: To give the classic think tank answer, yes and no. Let’s start with the no, not unusual. Military forces have been on the border continuously since the establishment of JTF-6 in 1989 to help combat drug smuggling. The levels have varied depending on the perceived level of need, the availability of forces, and the politics of immigration but continued in both Republican and Democratic administrations. The chart below shows these levels over time. Data before 2006 is sparse but the numbers were low, as the points from the 1990s show.
This chart also shows why this deployment might be unusual. The first deployment of 1,500 troops fits within the historical pattern. Expanding that to 10,000 troops would be on the high end. Going substantially beyond that would constitute an unprecedented level.
Q6: Is this an appropriate mission for the military?
A6: The military has supported law enforcement on the southern border for over 30 years with strong bipartisan support, so the answer must be yes. Elected officials get to make that decision. However, the number of troops and their roles have been limited.
President Trump sent troops to the border to emphasize its importance. Other presidents have done the same. However, it would be a mistake for the military to take over this mission. Stopping criminals is a law enforcement activity for which the military is poorly suited. Military personnel are trained and equipped to destroy enemy forces. On deployments, troops regard civilians as a potential threat. Law enforcement personnel view civilians as citizens who require protection and have extensive rights. Even illegal immigrants have human rights that must be respected.
Securing the border is also part of President Trump’s “America First” policy. That has strong support from the U.S. people in the election and polling. However, if the scale increases to the point where it involves pulling troops back from overseas commitments, then it entails strategic trade-offs far beyond what has been discussed so far.
Q7: Will the deployments hurt military readiness to respond to overseas crises?
A7: Again, yes and no. Having these units unavailable for a few months is not a major gap in capability. Many units on the border will do functions similar to their wartime mission. There is training value when support units deploy from their home base and perform these functions in an operational environment.
However, if deployment of active-duty units extends for many months or years, then readiness will suffer. These units need to do other training that can only be done on a military base, for example, weapons firing. This is not as serious a problem for the National Guard as they generally deploy to crises later.
Q8: What are the long-term prospects for these deployments?
A8: The EOs talk about this being a long-term military campaign. That’s not unreasonable since troops have been on the border for 30 years, and the challenge continues unabated. As discussed earlier, active-duty military personnel are not particularly good at law enforcement and are needed for war-fighting missions. Instead, contractors, the National Guard, and an expanded BP should replace the troop surge as quickly as possible. Contractors can do any construction that the military can do, plus more complex projects because that is their full-time job. The National Guard, as a state organization, is more familiar with domestic tasks. Expanding BP is the ultimate solution to personnel needs because it has law enforcement authority and is trained specifically for this mission.
Over time, the size of BP has increased enormously, from 4,100 in 1990 to 23,500 today. Most of that growth occurred between 1994 and 2010, but there has been some growth in recent years. If this is indeed an emergency, as the administration argues, then BP should expand further and its budget increase commensurately. Indeed, President Trump’s EO Protecting the American People Against Invasion, section 21, directs recruiting more BP agents, although it does not specify a number. This is an appropriate action for the policy goals laid out.
Q9: How much is this going to cost?
A9: Not much in the short term, but potentially a lot in the long term. Active-duty military personnel don’t cost much in this operation because their salaries and some operations funds are already included in the budget. There will be additional costs for transportation and temporary housing, but these are unlikely to be very large. National Guard troops, if they are used, require more funding because budgets include only 38 days a year for training, not the 365 days that would be needed if put on active duty full-time. Converting one National Guard member from part-time to full-time costs about $190,000 per year.
Additional BP agents cost about $200,000 per year, so adding another thousand would cost about $200 million per year. Recruiting may be challenging in an economy with low unemployment, but BP is offering $20,000 bonuses.
The cost of contractors is difficult to estimate because it will be driven mainly by decisions on the length and construction of the border wall. Contractors could also provide some services like transportation and maintenance that the military provides.
The fact that active-duty troops are already in the budget, whereas other forces require new resources, might make some budgeteers inclined to save money by using active-duty forces. However, this would be a false economy. The cost would be paid in reduced military readiness and, perhaps someday, in blood.
Mark F. Cancian (Colonel, U.S. Marine Corps Reserve, ret.) is a senior adviser with the International Security Program at the Center for Strategic and International Studies in Washington, D.C.