There are plenty of questions about the legality and effectiveness of such a move. US companies and consumers—not Mexico—are likely to suffer the bulk of the consequences of such a tax, an economic reality reflected in US stock markets’ steep drop this morning.

Nonetheless, US officials laid out what they want Mexico to do in a call with reporters last night: build a wall. Not on Mexico’s border with the United States, but its own southern border.

Image: CIA.gov

Mexico “must take significant action to secure their southern border,” said Kevin McAleenan, the new acting head of the Department of Homeland Security.

Unlike the United States, where the border with Mexico stretches for 2,000 miles and across four states, Mexico’s border with Guatemala and Belize is only a 150-mile stretch. The country could control the “visible, predictable” migration from Central America through “one Mexican border state” with “both natural and transportation chokepoints,” McAleenan said. He also said the United States hoped to partner with Mexico to help migrants seek asylum “in the first safe space they reach.”

Mexico has its own immigration crisis, as Quartz’s Ana Campoy wrote last month. Not all of the migrants fleeing violence in Central America are trying to get to the United States. Many of them apply for asylum in Mexico, too. As a result, Newly-elected Mexican president Andrés Manuel López Obrador is actually already working on his own sort of wall. Mexican officials refer to it as a “containment belt” of border patrol forces.

Raising taxes on Mexico and building walls is likely not a long-term solution to the problem. As Campoy wrote, “Any solutions will likely have to tackle its roots: extreme violence and poverty in Guatemala, El Salvador, and Honduras.”

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