Texas Sen. Ted Cruz has called for increased surveillance in Muslim communities in the United States in the wake of last week’s terrorist attacks in Brussels–and two national security experts, including a Republican member of Congress, were critical of the GOP hopeful’s plan.

“To send inflammatory messages could actually have an unintended consequence,” said House Homeland Security Committee Chairman Michael McCaul (R-Texas).

He added that Muslim communities are situated very differently in Europe, noting that they tend to be more segregated and thus easier for members of those communities to become radicalized. “In Europe it’s very segregated, and you have the diasporas in Belgium that I saw,” he said. “And they’re being radicalized because they’re not assimilated with the culture. I don’t think we have that same situation in the United States.”

John Miller, the deputy commissioner of intelligence and counterterrorism for the New York Police Department, also criticized Cruz’s plan.

“When you have people campaigning through fear and using that as leverage, and then giving advice to police to be the cudgel of that fear, that’s not the direction American policing should be taking in a democracy,” he said.

“Listen, we’re the proudest country on the planet and that’s because we have been a leader on freedom and human rights and everything else,” Miller continued. “I think in our history if there are moments of shame it would be Japanese internment, the Red Scare and McCarthyism, torture after 9/11–these are things that on reflection, through history, the American people have rejected.”

The two men also addressed the susceptibility of the United States to the kind of terrorist attack that killed dozens in Brussels last week, as well as what officials can do to prevent similar attacks here.

McCaul reassured that the American people are being protected, including additional security at airports and other transit hubs which were the target of the ISIS attacks in Brussels. “We are ramping up security at train stations, at airports, at subway systems using canines and other things both visible and invisible,” he said. “I want to give the American people assurances that we are protecting them.”

Still, he noted that there are two main concerns for preventing similar attacks in the U.S.: first, Americans already in the country who have been inspired by the attacks; and second, the foreign fighters that left the U.S. to join ISIS and have since come home.

“The idea that there are ISIS followers in the United States talking to ISIS in Raqqa and being influenced by them, and the thing that is the biggest challenge to federal law enforcement is the fact that they’re communicating in darkness,” he said, referring to encrypted communications. “If you can’t see what they’re saying in advance, it’s hard to stop it.”

Still, McCaul said, the U.S. has advantages in dealing with these kinds of threats that Europe doesn’t.

“In many ways Europe is in a pre-9/11 posture, they have many intelligence and security gaps,” he said. “The phenomena here is a foreign fighter threat, the revolving door from Europe to the region in Iraq and Syria and back through Turkey, back into Europe … it’s one of the greatest threats that Europe has because they’re not prepared for it from a security standpoint.”

Miller, explaining how the NYPD responds to an international incident of terrorism, said the agency’s response is threefold: first, they work to secure potential major targets in New York City, bringing in additional security as soon as the attack happens.

Second, they look for any possible New York connection to “make sure that we don’t have a threat that needs to be chased here.” At first glance, he added, it’s always difficult to tell whether a terrorist attack is an isolated incident or indicative of more to come around the globe.

And third, the NYPD sends officers and detectives to the scene of the attacks to see what American law enforcement can learn from the attacks or the way they were handled locally. “We study, with the local authorities, the attack and the response to see what we can bring back home to sharpen or hone our response,” he said.

He noted that many previous attacks have either been inspired or enabled by ISIS, but that Brussels is an example of something even more dangerous: attacks that were actually directed by ISIS.

“That’s teams under the command and control of ISIL sent from Syria to western Europe,” he said, referring to an alternative acronym for the group.