(CNN) Few groups have incited the ire of President Donald Trump more than MS-13 for the gang's recent vicious attacks and gruesome killings on US soil.

Charging that dangerous gangsters and criminals from Central America have been entering the United States through Mexico, the Trump administration in April launched a "zero tolerance" policy that has led to the prosecution and deportation of any adult caught illegally crossing the border.

There is no question the MS-13 gang must be stopped. It is a vile organization of hoodlums with no regard for life. But to entirely turn our backs on those who are trying to escape from being terrorized by the gang ignores the role that our government played in its monstrous evolution.

On the ground

Within an hour of landing in San Salvador, the capital of El Salvador, in 2005, where I was reporting on MS-13 for the National Geographic Channel, I was informed that a member of the notorious street gang had just been assassinated in the middle of the city. With my luggage in tow, I headed straight to the homicide location, where I saw a young man face down in a pool of blood, his body riddled with bullet holes.

I had reported on a number of different gangs in cities across America, but here I was in a country that was being terrorized and overtaken by street gangs, the largest of which was MS-13. What was astounding to me at the time was that 15 years prior to my visit, El Salvador had virtually no street gang presence.

MS-13 consists mostly of Salvadorans, but there are many Hondurans and Guatemalans who claim allegiance to the gang as well. To understand how MS-13 grew to become one of the deadliest gangs in the world, you have to understand the role the US played over the past four decades in the Central American countries from which most of these gang members come.

Money for fuel

A gruesome civil war between the government and Marxist guerrillas in El Salvador from 1980-1992 claimed 75,000 lives . The United Nations Truth Commission found that Salvadoran government forces, which included military officers trained by the US, paramilitaries and death squads, were responsible for more than 85 percent of the killings and torture.

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One of the most brutal conflicts in Latin American history was that of Guatemala's 36-year war in which, according to a truth commission, more than 200,000 mostly indigenous people were killed after being accused of being sympathetic to leftist guerrillas. The US supported the government, despite knowing of its egregious human-rights abuses.

Honduras did not have a civil war but became a staging ground for the various conflicts in neighboring Central American countries, including for US-backed groups.

A gang is born

Years of brutal armed conflict have left the region utterly destabilized and led hundreds of thousands of people to seek refuge in the United States. Many Salvadorans began to settle in the barrios of Los Angeles in the early 1980s. In order to protect themselves from already established neighborhood gangs, a group of them formed their own gang called Mara Salvatrucha or MS-13.

It initially consisted of a bunch of heavy metal enthusiasts who chose devil horns as their insignia, according to the International Committee of the Red Cross. They would grow to become one of the deadliest gangs in L.A. and throughout the country.

In the early 1990s, ICE's precursor, the Immigration and Naturalization Service, began rounding up thousands of alleged criminal gang members and deporting them back to their countries of origin — even though many had left their homelands when they were small children fleeing war and had never been back since.

These new, criminalized arrivals began to wreak havoc on the streets of El Salvador, Guatemala and Honduras — countries that were still reeling from years of conflict and destabilization. It was a deadly combination . The gang problem exploded. As I witnessed in El Salvador in 2005, the country was paralyzed with fear of gangs like MS-13. By 2015, it had become the most murderous country in the world

Give me shelter

In 2014, a massive wave of unaccompanied minors began showing up on the US-Mexico border, mostly from El Salvador, Guatemala and Honduras. Most had been sent for by family members who had previously settled in the US in an attempt to create better and safer lives for themselves and their children.

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As I experienced when reporting on the latest wave of MS-13 killings in Maryland for the premiere episode of CNN's " This Is Life With Lisa Ling " Season 5, newly arrived unaccompanied minors are continuing to come to the US and are being preyed on by an emboldened MS-13. They and their families, both in the US and back in their home countries, are threatened with death if they don't ally with the gang. Law enforcement officials in Fairfax County, Virginia, told me that violence is ordered from El Salvador.