Department of Homeland Security Secretary Alejandro Mayorkas said Wednesday during a House Homeland Security hearing that domestic extremism is the most threatening to national security.

“Right now, at this point in time, domestic violence extremism, the lone wolf, the loose affiliation of individuals following ideologies of hate, other ideologies of extremism, that are willing able to take those ideologies, execute on them in unlawful, illegal, violent ways, is our greatest threat in homeland right now,” Mayorkas told the House panel.

Mayorkas also spoke via Zoom about the crisis at the U.S. southern border and the plan to crack down on illegal migrants.

Moreoever, he confirmed that Department of Homeland Security (DHS) officials were executing a plan to address the crisis at the border.

“We have a short-term plan, a medium-term plan and a long-term plan and we’re executing on all fronts,” Mayorkas said. “To address the situation at the border that’s upon us right now takes time and we are working around the clock to do it. This is what we do and we will succeed. I believe in the men and women of the Department of Homeland Security and I believe in our commitments, our capabilities and we will get the challenged tackled.”

“But we will not waver in our commitment to succeed. That is our job. We will also not waver in our values and our principles as a nation. In the Department of Homeland Security, we can and we will tackle the many challenges we face while complying with our legal obligations and honoring our nation’s values and principles.”

“We are a nation of laws but we are also a nation of immigrants,” Mayorkas said.

The influx of unaccompanied minors at the border is of high concern to DHS officials. Mayorkas said that DHS officials are doing everything in their power to keep the young children safe and secure.

“I was on the border a few weeks ago and I saw the heroism, the true heroism of the men and women of the United States Border Patrol. I saw them undertake personal sacrifice to not only ensure that the border is secure but that the needs of the very young children are taken care of,” Mayorkas said.

In a statement Tuesday, Mayorkas said that the number of unaccompanied minors attempting to cross the U.S.-Mexico border is expected to reach its highest peak of the past two decades.

DHS officials expect the number of unaccompanied migrants children to continue increasing throughout the year and estimate that more than 117,000 will arrive to the U.S. this year, making it the largest number of migrant children to have arrived since President Obama was in office.

Watch the House Homeland Security Hearing here.

Follow Annaliese Levy on Twitter @AnnalieseLevy