Homeland Security Secretary Alejandro Mayorkas warned in an interview Sunday on ABC’s “This Week” of a “very difficult threat landscape” in the wake of the New Orleans truck attack.

And Republican Rep. Michael McCaul, chairman emeritus of the House Homeland Security Committee, noted the resurgence in the Middle East of ISIS, the extremist group which the New Orleans suspect said he was inspired by.

Early New Year’s Day, 14 people were killed and dozens more were injured after Shamsud-Din Jabbar, a 42-year-old Army veteran drove a pickup truck through a crowd on New Orleans’ Bourbon Street, authorities said. The suspect, a U.S.-born Army veteran from Texas, posted videos online before the deadly rampage “proclaiming his support for ISIS” and mentioning he joined ISIS before this summer, according to the FBI.

“We have not only the persistent threat of foreign terrorism — that, of course, created the Department of Homeland Security — but we have adverse nation-states, and for the past 10 years, we’ve seen a significant increase in what we term ‘homegrown violent extremism,'” Mayorkas told anchor George Stephanopoulos. “It is a very difficult threat landscape, and it is why that we as a community — not just the federal government, but state and local officials and residents — need to be alert to it and take the precautions necessary to avoid violence from occurring.”

Mayorkas said his office worked with local law enforcement and “took additional sweeping measures” to ensure New Orleans’ annual Sugar Bowl college football game could safely go on after the attack.

Despite immigration being the department’s “highest responsibility,” Mayorkas emphasized that the New Orleans attack was unrelated to issues at the southern border.

“The assailant who perpetrated the terrorist attack in New Orleans was born in the United States, raised in the United States, and served in our armed forces,” he said. “It is not an issue of the border.”

Mayorkas said he has been in touch with South Dakota Gov. Kristi Noem, President-elect Donald Trump’s pick for DHS secretary.

“I have spoken with Governor Noem a number of times, including on New Year’s Day and immediately thereafter, with respect to the horrific terrorist attack, and we have spoken substantively about the measures that we take, and I am incredibly devoted to a smooth and successful transition to the success of Governor Noem, should she be confirmed as the Secretary of Homeland Security,” he said.

McCaul, who also served as chairman of the House Foreign Affairs Committee, said the resurgence of ISIS in Afghanistan and Pakistan “concerns me greatly.”

McCaul advised the Trump administration to be wary of attacks by those who become radicalized online, urging officials to “pay attention to the social media and connect the dots before these events happen.”

“You really have two types of threats. One is operational, the other one is inspired attacks radicalized over the internet,” McCaul said. “They’re both equally lethal, and they need to be focused on to stop it.”

McCaul was also asked about the war in Ukraine and how he expects Trump to address it. Some of McCaul’s Republican colleagues have questioned the U.S.’s continued assistance to the country as it fights against Russia and Trump has promised to end the war quickly.

The congressman said retired Army Lt. Gen. Keith Kellogg, Trump’s pick for the newly created position as envoy to Ukraine and Russia, “believes that we cannot afford to lose Ukraine to Russia.”

“That would be a horrible foreign policy decision that would put us in the position of losing to Russia, and Ukraine, and threatening Eastern Europe,” McCaul said.

McCaul said Russia’s threat extends beyond the region.

“And the fact is, George, I can’t overemphasize, as I have to my colleagues, it’s not just Putin. Putin is aligned with Chairman Xi in China, who threatens the Indo-Pacific. He’s also aligned with the ayatollah in the Middle East who we have seen threatened Israel. And they’re all in this together. And [North Korean leader] Kim Jong-un sent 10,000 troops of his own to fight Ukraine’s,” he said.

McCaul said he believes Ukraine needs more “leverage” in negotiating a deal than the Biden administration has provided.

“I think President Trump does want to end the war, have a peaceful negotiation. We’re all for that, but it’s got to be on terms that do not throw Ukraine under the bus,” he said. “They were thrown under the bus in the Budapest agreements where they gave up all their nuclear weapons in assurance for security. And guess what happened? There was none. And if there is a deal cut, we have to have teeth in that enforcement agreement, such that if Russia ever invades again, there will be consequences because they gave up all their nuclear weapons.”