Congressional lawmakers met with men, women and children detained at the international boundary in several immigration detention facilities, where Democratic Leader Nancy Pelosi called President Trump’s “zero tolerance” immigration policy “an utter atrocity that debases America’s values and our legacy as a beacon of hope, opportunity and freedom.”

“Stop this inhumane, barbaric policy, rescind your actions, take responsibility for it,” Pelosi said in San Diego, according to KABC. “This is not about immigration. This is about humanity. It’s about family. It’s about who we are as a country.”

Pelosi said Republicans have a moral and legal responsibility to end new policies separating migrant children from their parents after entering the United States from Mexico.

“Blame for every mistreated child, heartbroken mother and father and broken family rests squarely on the president, and only he can end the trauma,” said Pelosi, who was joined at the podium with Rep. Juan Vargas, D-Calif., and the Congressional Hispanic Caucus.

Amid the international outcry, Homeland Security Secretary Kirstjen Nielsen said Monday that the growing crisis at the U.S.-Mexico border “is not new.”

“We will not apologize for the job we do or for the job law enforcement does for doing the job that the American people expect us to do,” Nielsen told the National Sheriffs’ Association during a speech in New Orleans. “Illegal actions have and must have consequences. No more free passes, no more get out of jail free cards.”

The separation of immigrant children from their parents at the border has drawn a barrage of criticism, targeting the policy instituted last month by Attorney General Jeff Sessions. That policy says that any adult who enters the U.S. illegally is to be prosecuted criminally.

U.S. protocol does not allow children to be detained with their parents because they, unlike their moms and dads, aren’t charged with a crime.

Fox News' Samuel Chamberlain and The Associated Press contributed to this report.