One of El Salvador’s former guerrilla leaders, who years ago traded olive drab for Irish tweeds and took up residence at Oxford University, can tell you exactly why his homeland is being torn apart right now by gang violence.

He can also tell you what that means to those of us who live under the delusion that the carnage in the streets of San Salvador this month—expected to get much worse this weekend—is not just a local problem in a faraway land.

Central America’s savagery is terrorism, pure and simple, says Joaquín Villalobos, and in many respects it is more horrible than the Middle Eastern brand. “Islamic terrorism decapitates and crucifies in its territories,” says Villalobos in a column for the Madrid daily El Pa í s. “In Latin America the criminals hang, decapitate, burn, chop up, and play soccer with the heads of their victims. In both cases terrorism is the method used to maintain authority.”

And Central America’s brand of terror is just around the corner from communities all over the United States, whether in the barrios of Los Angeles or at a derelict shopping mall next to a posh neighborhood on Long Island, as chronicled by Sarah Garland in her 2009 book The Gangs in Garden City.

The Salvadoran pandillas or maras, as the gangs are called, are in Washington State and in suburban Maryland on the fringes of Washington, D.C. Indeed, the FBI’s “National Gang Report—2013” (PDF), the most recent that’s been published, shows the two main Salvadoran groups, MS-13 and Barrio 18, are in just about every corner of this country. And, like other gangs, according to the FBI, they have infiltrated the U.S. military to get training and expand their influence. The feds also say that gang members show up on college campuses.

In fact, the Salvadoran gangs have roots almost as deep in the United States as they do in El Salvador itself. They started to grow in the 1980s, as hundreds of thousands of Salvadorans fled the civil war there, arriving in the U.S. to live, often without documents, on the margins of society. An estimated 40 percent of the population eventually “went north,” legally or illegally, to live and work.

El Salvador’s economy became dependent on the money sent back, but instead of going into the development of the country, most of the remittances went to buy imported consumer goods and the cash wound up in the hands of the very rich, who, in turn, spend it for their own protection and invest it abroad. Villalobos, the erstwhile revolutionary turned specialist in conflict resolution, concludes, “Exporting poor people has become the most lucrative business for the local oligarchs.”

Many of the immigrants’ and refugees’ children in the United States, often without documents and without futures, joined gangs on the streets and did time in prison, the graduate schools of violent crime. Then they were deported back to their home country with all their newly acquired contacts and skills. Eventually, hardened and brutalized, tattooed with the indelible badges of their criminal tribe, some of them came back again to the United States in a truly vicious circle of worsening violence. It was a blending of the gang culture that existed in Los Angeles with the phenomenal violence that El Salvador experienced during the war from 1980 to 1989, waged by right-wing death squads and guerrilla assassins, as well as by soldiers in the field.

The kind of gang violence that grew up in El Salvador is now endemic in Guatemala and Honduras, as well, and it is localized terrorism as extreme as anything seen on the planet. Those three little countries rank among the five countries with the highest murder rates in the world.

The photographer and filmmaker Christian Poveda in his 2009 documentary La Vida Loca recorded the gang culture of cruelty and desperation in stunning detail. Soon after the film’s release, Poveda himself was murdered execution-style with four bullets in the head.

Over the last few days, the terror in El Salvador has brought virtually all of the country to a standstill: The slaughter of several bus and minibus drivers—five on Monday alone—has provoked a nationwide strike. Despite new waves of arrests, and the gangs’ hatred of each other, MS-13 and Barrio 18 are clearly out to show how powerless the central government really is.

In 2013, left-wing President Mauricio Funes negotiated a truce between MS-13 and Barrio 18 that dramatically reduced the country’s murder rate, but it ratified the power of the gangs in Salvadoran society, leaving them able to continue their protection rackets, their rapes, their drug dealing, and other crimes. By 2014, the murder rate was going up again, and Funes had to admit the truce had been a failure.

The government of his successor, former guerrilla fighter Salvador Sánchez Cerén, has said it is ready to put the army back in the streets to protect transport and combat the gangs.

A new round of Central American wars, and tragedies, may be about to begin.