In his convention acceptance speech, President Donald Trump asserted, “I will end the illegal immigration crisis by closing our border and finishing the wall, most of which I’ve already built.”

Erecting physical barriers along the Mexican frontier is certainly an important dimension of putting in place the long-overdue, modern, 21st-century secure border system that the United States desperately needs. Completing such wall-building projects is slow and time-consuming (although they certainly could be adequately financed with just a small fraction of the many tens of billions that Uncle Sam has dedicated to defending Ukraine). 

But beyond continuing to build the wall, President Trump will need to take emergency measures on Day 1 to stop the bleeding on the southern frontier.   

Obviously, the next Trump administration will start with a series of Executive Orders that terminate unlawful Biden-Mayorkas policies that release asylum-seekers into our country. Washington can control that, but fundamentally, a new era of modern U.S. border security also begins with no-nonsense diplomacy that compels Mexican authorities to cooperate.  

Above all, Washington must insist that Mexicans vigorously interdict all third-country nationals moving unlawfully to cross the frontier and agree to accept the return of all illegals who entered the U.S., regardless of nationality. Such bilateral cooperation would, as a first step, restore the Migrant Protection Protocols (better known as “remain in Mexico”). 

The leaders in Mexico City will no doubt see the re-election of President Trump by itself as a massive political shift. Under President Andres Manuel Lopez Obrador (AMLO), the Mexicans have been masters of realpolitik, manipulating the hapless Biden administration, while also sometimes rescuing it politically by slowing the embarrassing numbers of migrants moving north. 

The recent arrest of Sinaloa drug lords illustrates again the pathetic state of U.S.–Mexican law enforcement cooperation. For most of AMLO’s time in office, the pattern of on-and-off security cooperation has mainly been set to “off.”  It is no surprise that American law enforcement did not inform the Mexicans in advance of the recent arrests.

When President Claudia Sheinbaum assumes power in October, replacing AMLO, she will be willing, however grudgingly in private, to give priority to the new Trump administration’s call for a fresh start on security cooperation. Trump should make the most of whatever goodwill comes from Sheinbaum, but her fundamental ideological views on the “human right” to migrate are the same as her predecessor’s. Sheinbaum’s own inclination to continue the intermittency of Mexico’s security cooperation should not be doubted. 

In managing this Mexican zigzag, Trump must retake the initiative by implementing long-term measures that fundamentally remake the border security framework. The formula consists of fully deployed, modern land barriers; common-sense policy instructions to a reinforced and better-funded U.S. Customs and Border Protection and U.S. Border Patrol; and constant diplomatic pressure that ensures serious Mexican security cooperation. When cooperation flags, which is the historic pattern, there must be powerful negative consequences in the wider bilateral relationship.

Mexico’s economic and political leadership fully understands that their greatest national asset is geography: their ability to easily access the U.S. consumer market and send migrants north. This privilege has become even more prominent in recent years as commercial nearshoring in Mexico has grown into an international business strategy, capitalizing on Washington’s economic pivot away from China. 

The new Trump administration must concentrate on this legal movement of commerce and people across the frontier onto U.S. territory as the fulcrum to compel Mexican cooperation and fundamentally change the border. One effective option, of course, is the threat to impose commercial tariffs, as Trump and Secretary of State Mike Pompeo effectively demonstrated in leveraging Mexican border cooperation in 2018. 

The next Trump administration should certainly continue this diplomacy, using the tools, however limited, under the United States-Mexico-Canada trade agreement to compel cooperation. In fact, USMCA will go through a renewal evaluation in 2026 that can be very helpful. Yet the threat of imposing tariffs under USMCA is likely to be more complicated for President Trump in 2025, compared with 2018, because Mexico has emerged as the biggest U.S. trade partner.  

Powerful commercial special interests are already deployed and doubtless gearing up to politically resist a Mexico policy that links bilateral trade to border security. The business lobby in Washington will spin the usual superficial arguments: Tariffs on Mexican commerce only hurt American consumers; legal trade is always good and must be viewed separately from Mexico’s criminality and corruption. 

That is why the next Trump administration should also consider another choke point: legal movement of Mexicans into the United States. U.S. law already fully empowers the president to interdict and stringently to control this legal movement under the Immigration and Nationality Act (INA), Section 212(f).  The statute is very clear: 

Whenever the President finds that the entry of any aliens or of any class of aliens into the United States would be detrimental to the interests of the United States, he may by proclamation, and for such period as he shall deem necessary, suspend the entry of all aliens or any class of aliens as immigrants or nonimmigrants, or impose on the entry of aliens any restrictions he may deem to be appropriate.

The “suspended entry” power means that the Department of Homeland Security (or more exactly, U.S. Customs and Border Protection) is authorized to deny the admission onto American territory to designated groups of foreigners, in this case, Mexicans who arrive at all U.S. entry ports: land, sea, and air. Section 212(f) also authorizes the Department of State to suspend the issuance of visas to Mexicans in American embassies and consulates.

Section 212(f) is a powerful presidential tool, enacted by Congress to allow the executive, for national security, to specifically link a disastrous international situation to the legal movement of a foreign population group. The law contemplated a situation that in many ways exactly reflects the current U.S.–Mexican border reality.  

To be clear, 212(f) would not stop clandestine asylum seekers from showing up on our land border, but by suspending legal admissions of Mexcians, it would immediately compel the Mexican government to join the U.S. in unprecedented new security cooperation.  Such cooperation would keep the vast majority of would-be asylees and other illegal migrants away from the U.S. border.

Like finishing the border wall, regularizing the application of 212(f) should be a basic building block of a comprehensive frontier strategy.  It is the best way to counter past Mexican practices of on-and-off cooperation. Mexico City’s failure or spottiness in working with the U.S. on a range of issues—law enforcement, extraditions, and repartitions—should be answered by Washington’s immediate imposition of 212(f), applied in stages to address the gravity of our security concerns.

Some may recall that the first Trump presidency issued a series of executive orders based on 212(f)—technically they were “presidential proclamations”—to suspend entry, as well as refugee and visa processing, of nationals from a number of countries ruled by dodgy regimes (including Iran, Iraq, Libya, Somalia, Sudan, Syria, Yemen, North Korea, and Venezuela). Trump justified using 212(f) against these countries because U.S. authorities did not believe that they could properly vet the nationals who lived under these regimes before they entered American territory. 

Most will recall the tsunami of media-orchestrated invective and the lawsuits against Trump’s strategy. The opponents tendentiously called the use of 212(f) a “Muslim ban” and worse. The vociferous and propagandistic attacks, predictably, eclipsed any real policy discussion on the effectiveness and wisdom of using 212(f) as a border security tool to protect the American homeland.  

Such a discussion would have clarified that the president can apply 212(f) both because the foreign travelers themselves may be unvetted and a security risk, but also because ending the movement of a country’s nationals into the U.S. can help moderate the bad behavior of its government. Thus, Section 212(f) is a legitimate diplomatic weapon, fundamentally designed to advance the wider U.S. national interest.

In a landmark decision that border-security advocates everywhere should carry in their pockets, the U.S. Supreme Court upheld President Trump’s use of 212(f) and even strengthened its reach. In Trump v. Hawaii, the high court overturned lower decisions that tried to limit 212(f) and stated that the Immigration and Nationality Act “exudes deference” to the president in excluding foreigners from entering the country.  

Moreover, the high court stressed the realpolitik nature of 212(f): “Presidents have repeatedly suspended entry not because the covered nationals themselves engaged in harmful acts but instead to retaliate for conduct by their governments that conflicted with U.S. foreign policy interests” (emphasis added).

This clarification answers critics who incorrectly assert that the use of 212(f) is restricted only to situations in which American authorities cannot properly vet foreign travelers. It bears repeating: Section 212(f) is not only a border security tool, but a diplomatic weapon that allows Washington to serve the wider national interest by curtailing the entry of foreigners into the U.S.  Except for Trump, modern presidents tend to ignore 212(f) and have reached to other diplomatic tools, in many cases less effective, such as hard-to-enforce economic sanctions and clumsy military pressure.  

U.S. policymakers need to study 212(f), which goes right to the heart of addressing “frenemy” regimes, like the one in Mexico City, whose economic prosperity is very much tied to the movement of their nationals into the United States. AMLO never forgets, despite his rants against American conservatives and Republicans, that Mexicans in the U.S. send back to their homeland almost $59 billion annually, according to official sources. These remittances surpass the country’s foreign income generated from tourism, oil exports and most manufacturing exports.  

There is also a case to be made that proclaiming 212(f) will be politically easier for President Trump than imposing commercial tariffs. While there are certainly special interests in Washington invested in the influx of Mexicans into our country (e.g., immigration lawyers, cheap labor interests), that lobby does not match the political firepower of U.S. commercial interests that attend to protecting USMCA.  

Finally, a compassionate word about the Mexicans. Americans recognize that most regular Mexicans are not responsible for the disastrous border security situation or the out-of-control criminality and corruption that endanger the long-term stability of both countries. Most are normal people caught between their own corrupt and dysfunctional government on the one hand, and the criminal cartels on the other.  While it will be hard, Trump’s application of 212(f) offers them hope, long term, that there can be change even inside Mexico.

There was an era, years ago, when Americans, whether tourists or those who lived on the frontier, many of Mexican heritage, routinely traveled back and forth across the border. The border region was often rough, but not the brutal crime zone of today. That time long ago ended; it has been lost to rampant criminal cartels that Mexican City authorities basically accommodate.   

It is clear that the Mexican federal government (and under Biden, America’s own inept national leadership) is prepared to live indefinitely with this unacceptable reality. One of the ways out of this disaster, the start of a path into a new modern era of border security that benefits both nations, could come through the robust use of 212(f). Let’s hope that is exactly what Trump is planning for Day 1.