Vice President Mike Pence held a meeting with the presidents of El Salvador, Guatemala, and Honduras in Guatemala City on Thursday, telling them the “exodus” of migrants from their countries into the United States must end.

Pence told the assembled Central American leaders that President Donald Trump sent him to Guatemala because the U.S. is facing “another crisis on our southern border.”

“I’m sad to report to the Presidents gathered here that the vast majority of those entering our country illegally are from your countries,” he added.

Pence proceeded to describe the magnitude of the problem and firmly told the Central American leaders they are responsible for the conditions that make so many people desperate to flee their countries:

As we discussed, the numbers are staggering. Since the start of this year, more than 150,000 Guatemalans, Hondurans, and Salvadorians have left their homes and made the often-dangerous journey to the southern border of the United States, and sought to enter our nation illegally. While many claim asylum, few are fleeing persecution. Among, this flood of illegal migrants are human traffickers and violent gang members, like MS-13. But most are making the journey seeking economic opportunity, driven by the misguided belief that they can ignore the laws of the United States and enter our nation without consequences. I say with great respect to the Presidents gathered here: This exodus must end. It is a threat to the security of the United States. And just as we respect your borders and your sovereignty, we insist that you respect ours.

Pence followed up by saying the United States will always welcome legal immigrants who play by the rules, noting that his own grandparents immigrated to America by way of Ellis Island. He then stressed America’s sovereign right to enforce its borders and insist upon compliance with its immigration laws, quoting President Trump’s warning: “If you don’t have borders, then you don’t have a country.”

The vice president referenced the Obama and Bush-era policies for detaining the children of illegal immigrants that suddenly became the focus of obsessive media coverage under the Trump administration. He explained the best way to deal with family detention is to reduce the number of families who need to be detained:

President Trump has also taken action to keep families together while we enforce our laws and secure our border. And I’m grateful for the words of affirmation that have been expressed in our meeting today by the Presidents gathered here. Earlier today, the First Lady visited with children from your countries in Arizona. And as we discussed, we’re working to reunite families from your nations who have been caught trying to illegally enter the United States. In our country, we believe we can, as the Old Book says, “do justice and love kindness” at the same time. But ultimately, this crisis cannot be solved by America alone. And that’s what brought us together today. The truth is, weak economies, corruption, drugs, and violence are the root causes of this crisis. The United States has long partnered with your countries to address these challenges, and our efforts, as we discussed today, have made some progress. But as we now see at our nation’s southern border, the need for stronger action is more urgent than ever. And as we discussed, with great respect, our nation needs your nations to do more.

Pence stressed the need for deterrence to begin at the countries of origin, asking Central American leaders to tell their people “coming to the United States illegally will only result in a hard journey and harder life.” He more pointedly told them to stop indulging smugglers and allowing them to advertise their services to migrants.

Pence concluded his remarks by speaking directly to the people of Central America:

So as I close, permit me to deliver a message directly to the people of Guatemala, and Honduras, and El Salvador, straight from my heart, and straight from the heart of the American people: You are our neighbors. We want you and your nations to prosper. If you want to come to the United States, come legally, or don’t come at all. If someone tells you they can bring you or your children to America outside the law, don’t believe them. Don’t risk your lives or the lives of your children by coming to the United States on the road run by drug smugglers and human traffickers. Hold on to your homes and your homeland. Hold on to your children. Build your lives in your homes, and know that the people of the United States of America will keep working every day for a brighter future our people and people all across this new world.

The general tone of the response from the presidents of El Salvador, Guatemala, and Honduras was understanding that their border security has been too lax and they have persistent problems with organized crime, including human traffickers.

President Salvador Sanchez Ceren of El Salvador spoke at length about the humanitarian necessity of treating illegal immigrant families well and reuniting them as soon as possible without saying much about where they would be reunited, beyond a brief mention of the “El Salvador Seguro” package of social programs intended to “strengthen the experience of returning home to El Salvador.”

President Juan Orlando Hernandez of Honduras offered a broad vision of a “multi-headed monster” that includes drug, gun, and human traffickers.

“Today we see how migration is going up, going down, in cycles. It has gone down in the past also in Honduras, but we know that increasingly it is necessary to tackle the root of the problem, which involves dismantling the criminal world that engages in the trafficking of persons,” Hernandez said.

“Today, as we leave this meeting, Honduras is going to improve its presence and intelligence in policing and armed forces to be even more successful by arrest and dismantling the gangs of criminals that are so harmful to our people by stealing their money and deceiving them to take them to a place where they will likely find hopelessness and a physical and psychological harm,” he vowed.

President Jimmy Morales of Guatemala pledged to work against organized crime and strengthen border controls. He also repeated his request for Temporary Protected Status for Guatemalan refugees in the United States in light of the recent volcanic eruption in his country.

Morales appealed to the media for help in spreading the word against human traffickers:

Finally, to the media I say, you play an extremely important role in raising awareness of the people that should not travel the way they have been doing, by using smugglers or coyotes and people who deal with life as it were merchandised. You, together with us, the rulers and all citizens who are conscientious and responsible for the construction of this nation, we all need to engage in awareness-raising campaigns for free — to show to the Guatemalan people and the people of any other nationality the risks that are run and the need to abide by proper procedures to remain within the framework of legality of all countries.

Pence and the Central American presidents are dealing with a problem the Obama administration reluctantly acknowledged but only fitfully addressed: it is very difficult to spread even the most carefully crafted and enthusiastically promoted message of deterrence if migrants understand the reality is open borders, especially for children and adults who bring children with them.

No conceivable public relations campaign could suppress the knowledge that “catch and release” policies grant effective access to the United States after minimal hardship. Many things can be said about people who scrape up enormous sums of money and hand them over to violent gangsters, along with their children, but they are not delusional. They know they are taking a terrible risk, but they believe the risk is worth taking. As long as they have a good chance of “winning” by setting foot on U.S. soil, they will play the game.

The commitment to developing the Northern Triangle of Central American into a place people are not desperate to escape at all costs is a tacit admission that reducing the value of the service offered by smugglers is vital to putting them out of business. As Vice President Pence made clear, human smuggling is a lucrative subsidiary to gangsters whose other operations are even greater threats to the security of North, Central, and South America.