It is just over four months since police in the town of Iguala in the impoverished southern state of Guerrero opened fire on a group of rural teaching students, killing 6 and wounding 17. Another 43 disappeared after falling into the hands of the authorities. Now, the Mexican government of President Enrique Peña Nieto has moved to declare the crime solved and the case closed for the most transparent political motives.

Peña Nieto and his attorney general, Jesus Murillo Karam, both made statements to this effect on January 27, one day after a massive demonstration once again filled Mexico City’s central plaza, the Zócalo, marking the four-month anniversary and indicting the Mexican government for the crime.

The atrocity carried out last September has shaken the country, exposing the chasm separating the masses of people from the political establishment and the ruling financial and manufacturing elites. Every single party of the Mexican bourgeoisie, from the ruling PRI (Institutional Revolutionary Party), to the right-wing PAN (National Action Party), to the pseudo-left PRD (Party of the Democratic Revolution) and Morena (the Movement for National Regeneration of Andrés Manuel López Obrador), has been implicated in this historic crime.

It fell to Murillo Karam to present before the television cameras what he declared the “historical truth” of the events in Guerrero—what would be more appropriately described as the “official story.” According to this account, the students came to Iguala on September 26 to raise funds and seize buses to transport them and their fellow students from the Ayotzinapa Normal School (as rural teachers’ colleges are known) to a demonstration in Mexico City.

The Iguala police, acting on the order of the city’s PRD mayor, attacked the students, killing three of them as well as three bystanders. The 43 students who were abducted were then turned over to police from the neighboring town of Cocula, who in turn handed them over to a drug gang known as Guerreros Unidos. Thrown one on top another and transported by truck to a garbage dump, many of the students were said to have died of asphyxiation, while those who survived were dragged from the vehicles and shot to death execution-style. Afterwards, the bodies were piled onto a pyre and burned, with the charred remains stuffed into garbage bags and dumped in a nearby river.

According to this official story, the mass murder was all a question of mistaken identity, with the assassins taking the students for members of a rival drug gang.

Parents of the disappeared students angrily denounced the attorney general’s performance, accusing him of attempting to shut down the investigation before national parliamentary elections scheduled for June.

The families and their attorneys have charged that the case is being wound up without having uncovered any scientific evidence of the students’ deaths, and under conditions in which principal figures in their disappearance have yet to be apprehended. Moreover, they charge, the government is deliberately covering up the role of the army battalion in Iguala, as well as that of federal police and other political officials on both the state and federal levels, all of whom have been implicated in the crime.

The anger of the families and their supporters was only deepened by the remarks of Peña Nieto, who effectively told Mexicans to get over the disappeared students and allow his government to move on.

Speaking to an audience that included the US ambassador, the president said that while there had to be “punishment for those who were responsible,” Mexicans “must take the path of continuing forward to assure that Mexico has a better future.” What is “important,” he added, is that “we do not remain stopped, paralyzed and at a standstill.”

In other words, the mass protests must be suppressed so as not to become an impediment to the “Pact for Mexico,” the slate of “reforms” introduced by the government to privatize the country’s oil sector and carry out similar measures in the education, telecommunications and finance sectors. Targeted for elimination in the education “reform” are the Escuelas Normales, the rural teachers’ colleges, like that of Ayotzinapa, which were a product of the Mexican Revolution. This drive to subordinate education to the profit system is the real dynamic behind the crime against the students.

US imperialism is a full partner in this drive and has the blood of the disappeared students on its hands. When Peña Nieto visited the White House earlier this month, Obama praised him as a “reformer,” while US officials hailed his government for its privatization of oil, its growing economic integration with the US, and its bid to increase “competitiveness” through the destruction of workers’ rights.

The butchery carried out in Guerrero was not an aberration, but an integral part of this process, which is bound up with the global interests and ambitions of US imperialism. This was spelled out in a document drafted recently by an “independent task force” of the US Council on Foreign Relations entitled “North America: time for a new focus.” Co-chairs of this task force were David Petraeus, former head of the CIA as well as commanding general in the US war in Afghanistan, and Robert Zoellick, the ex-president of the World Bank.

The report states: “It is time for US policymakers to put North America at the forefront of a strategy that recognizes that North America should be the ‘continental base’ for US global policy.” It predicts that an integrated North America will “have the potential to again shape world affairs for generations to come.” Key to this process, it states, is “Mexico’s ambitious structural reform agenda,” above all, “historic reforms” in the energy sector.

What is proposed is the consolidation of a “Fortress North America” as the launching pad for US imperialism’s drive to subordinate every part of the world economy and every corner of the globe to its interests.

This strategy, which Washington is pursuing with ever more reckless military interventions and provocations, from the Middle East to Ukraine to the South China Sea, goes hand in hand with social counterrevolution and the assault on the democratic rights of the working class at home.

With the drive to tie Mexico ever more tightly to the war chariot of US imperialism, this process has found a particularly horrific expression in the events in Guerrero. The same murderous methods, however, are being prepared against the working class north of the Rio Grande.

Against the imperialist attempts to consolidate a “Fortress North America,” the working class must advance its own solution—the unification of the Mexican, US and Canadian working class in a united struggle against capitalism. This requires the building of a new revolutionary and internationalist leadership, embodied in the International Committee of the Fourth International.