WASHINGTON — The terrorist attacks in Brussels are further evidence the United States needs a crackdown on people entering the country, Donald Trump said Tuesday.

“I would close up our borders to people until we figure out what is going on,” Trump said on Fox News. “They could be ISIS, they could be ISIS-related. We just don’t learn.”

Calling Brussels an “armed camp” and a “horror show,” Trump also said that terrorist suspects, including alleged Paris attacker Salah Abdeslam, be water-boarded or otherwise tortured to get leads that might prevent future attacks.

Later, he clarified that he doesn’t want to ban everyone from coming into the country, saying only those with “absolute perfect” documentation should be allowed in — and, for now, no Muslims.

Trump also told Fox Business News that it’s time to end the visa waiver program, which allows visitors from friendly countries, including Belgium and France, to enter the United States without visas for 90 days.

“Yes, it’s time to stop that, absolutely,” said Trump, who also called for stepped-up mosque surveillance.

His principal GOP rival, Texas Sen. Ted Cruz, also talked tough.

“We need to immediately halt the flow of refugees from countries with a significant al Qaeda or ISIS presence,” Cruz said in a statement.

“We need to empower law enforcement to patrol and secure Muslim neighborhoods before they become radicalized.”

Cruz later said in New York that that if he were president, he would resurrect the controversial monitoring program that targeted Muslims under former Mayor Mike Bloomberg and ex-Police Commissioner Ray Kelly.

“You would continue the proactive policing that we saw here in New York,” Cruz said. “You would reinstate the program.”

Asked on CNN whether he would support Cruz’s plan, Trump, a rare detente with his bitter rival, responded, responded: “Yes, I would. I think that’s a good idea.”

NYPD Commissioner Bill Bratton, however, was furious at Cruz’s proposal.

“I would remind the senator that he lives in the United States of America, and the statements he made today is why he’s not gonna become the president of this country,” Bratton said.

“We don’t need a president that doesn’t respect the values that form the foundation of this country.”

Meanwhile, Ohio Gov. John Kasich and Democratic contender Bernie Sanders called for unity with allied countries to defeat ISIS, along with increased intelligence gathering.

Hillary Clinton described Trump’s call for closing the borders “unrealistic,” but urged an increased police presence at soft targets, such as airport lobbies.