The database complicates that picture. Significant chunks of Mérida spending have indeed gone to civil society programs in Mexico in the past decade, largely through the U.S. Agency for International Development and the State Department; however, the government’s own records show that the Pentagon has taken the opposite track since 2011, doubling down on tactical training while moving away from human rights instruction. While the database captures the language proficiency and technical training courses one might expect to find in a binational security partnership, it also features extensive records of recent and large-scale training operations involving U.S. personnel in Mexico, including dozens of “unit-level pre-deployment training” missions involving upward of 140 marines at a time, combat shooting courses, martial arts courses, airborne parachute courses, tactical driving courses, asset interdiction courses, aerial warfare courses, and more.

“The top-line story that everybody’s giving is, all the Mérida spending is going to justice reform and it’s not just about shooting the baddies anymore,” Lettieri said. “I would say what the Pentagon is doing is ‘here’s how you shoot the baddies.’”

The information in the database, first organized by Security Force Monitor, a Columbia Law School project, shows that from 2007 to 2012, the U.S. provided tactical training to an average of 261 members of Mexican security forces annually. After 2012, that number jumped to 1,454. The Mexican marines were the primary beneficiary of the explosion in training, representing nearly 60 percent of the Pentagon’s students and receiving nearly half — $46.3 million — of the $101.2 million spent post-2011. From 2013 to 2019, while tactical training was surging, the Pentagon provided human rights training to just 27 students, only 12 of whom came from the Mexican military. Combined Pentagon and State Department funding on human rights training post-2012 came out to a mere $212,000.

Lettieri went into the project neither searching for nor expecting to find the post-2011 increase in tactical training, but as he continued to work with the data, the shift became clear. “When you look at it over time, it just jumps off the page that it’s tactical,” he said. It wasn’t just the marines, known in Mexico as SEMAR, receiving tactical training, he discovered. The army, known as SEDENA, also received extensive Pentagon support at the tactical level. The finding was significant because Washington has couched its embrace of the marines as allies in the drug war in Mexico in the perceived unreliability of the army as a trustworthy partner in matters of operational security and human rights. SEDENA has long been one of Mexico’s most powerful institutions; it has also been tied to many of the country’s worst state crimes, including the 2014 disappearance of 43 college students in the state of Guerrero.

The database provides just one glimpse into a much wider world of security exchanges between the U.S. and Mexico, Lettieri said, most of which is inaccessible to the public. It does not include, for example, information on the enormous array of arms Mexico purchases from the U.S. or where those arms ultimately end up, nor does it reveal anything about the extensive training and cooperation that occurs between state and local law enforcement agencies on the two sides of the U.S.-Mexico border. Thanks to the joint State Department and Pentagon report on foreign military training that’s delivered to Congress each year, “we have some ability to understand this section of U.S. interaction with Mexico,” Lettier said. Still, he added, “There’s a whole bunch of stuff we don’t know very much about.”

“That’s a key takeaway here,” he said. “There’s a whole bunch of money being spent, but we don’t have even this minimal kind of accountability.”