One of the reasons border apprehensions have dropped from their alarming peak in May is that Mexico has been pretty aggressive in stopping third-country nationals from traversing its territory on their way north to make bogus asylum claims so they can be released into the U.S.

But why has Mexico been willing to work with us like this? It’s especially curious because in the past, Mexico was not at all eager to help us limit illegal immigration, a pattern we might have expected to intensify with last year’s election as president of left-wing populist Andres Manuel Lopez Obrador (commonly known as AMLO, pronounced as a word rather than initials).

. . .

Rather, I think a big part of the explanation is that the current flow of illegals is mainly made up of foreigners, not Mexicans. . . .

Read the rest at National Review.