Washington — Homeland Security Secretary Alejandro Mayorkas on Sunday defended the Biden administration’s immigration policy following the deaths of 53 migrants who were abandoned in the back of a tractor trailer, saying U.S. immigration officials have repeatedly warned against traveling to the southern border.

“We have said repeatedly and we continue to warn people not to take the dangerous journey,” Mayorkas said in an interview with “Face the Nation.” “We saw so tragically in San Antonio, Texas, one of the possible tragic results of that dangerous journey and so many people don’t even make it that far in the hands of exploitative smugglers. And we continue to enforce immigration law, as is our legal responsibility.”

The secretary said migrants traveling through central America to the U.S.-Mexico border often receive false information from smugglers that encourages them to attempt the journey.

“They put their lives, their life savings, in the hands of these exploitative organizations, these criminal organizations that do not care for their lives and only seek to make a profit,” he said.

The deaths of the 53 migrants abandoned in the tractor trailer in the sweltering San Antonio heat appears to be the deadliest human smuggling case in modern U.S. history. Federal charges have been filed against four people allegedly connected to the deaths.

Mayorkas said the Biden administration is working closely with Mexico to break up caravans of migrants that seek to cross the border into the U.S., and said addressing the high number of migrant arrivals along the southern border is a “regional challenge that requires a regional response.”

“These are very sophisticated transnational criminal organizations. They have evolved over the last 30 years,” he said. “In the 90s I prosecuted them and they were much more rudimentary. Now, they are very sophisticated, using technology and they’re extraordinarily organized transnational criminal enterprises.”

But Mayorkas said the U.S. has also ramped up its efforts through technology and manpower, with authorities at the border saving more than 10,000 people this year.

“Can a truck get through sophisticated means? Sometimes, yes,” he said. “But I have to say, we have interdicted more drugs at the ports of entry than ever before. We’ve rescued more migrants. We’re seeing a challenge that is really regional, hemispheric in scope, and we’re addressing it accordingly.”

While the Biden administration continues to defend its immigration policy following record levels of migrant apprehensions in May and the deadly smuggling campaign in Texas, it received a win from the Supreme Court on Thursday, when the justices cleared the way for the administration to unwind the Trump-era “Remain in Mexico” policy.

Under the program enacted under former President Donald Trump, asylum seekers were required to await their court proceedings outside the U.S.

Mayorkas said the department is “pleased” with the decision and said the “Remain in Mexico” program has “endemic flaws” and “unjustifiable human costs.”