Donald Trump tells TODAY's Savannah Guthrie and Matt Lauer if he were president, he'd react to the Brussels attacks by being "very, very tough on the borders" and by using torture of suspects if necessary to try to obtain vital information.

"Brussels is a total mess,'' the GOP front-runner said in a live phone interview Tuesday. "They're just a city that used to be one of the finest and one of the most beautiful and one of the safest cities in the world, and now it's a catastrophic, very dangerous city where the police have very little control."

Blasts rocked the check-in zone of Brussels Airport and the Belgian capital's subway early Tuesday, killing dozens of people and injuring scores. According to sources, at least one and possibly multiple "suicide bombers" were involved in the attacks.

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epa05224807 2016 Republican presidential candidate Donald Trump delivers remarks at the American Israel Political Action Committee (AIPAC) Policy Conference in Washington, DC, USA, 21 March 2016. AIPAC is an American pro-Israel lobby group. EPA/SHAWN THEW SHAWN THEW / EPA

The attacks came just days after a raid in Brussels captured Europe's most wanted man, Salah Abdeslam, who is suspected of plotting the Paris terror attacks. If Trump were president and Abdeslam was a suspect in U.S. custody, he said he would use any technique necessary to extract information from him about any other potential attacks.

"Frankly, the waterboarding, if it was up to me, and if we changed the laws or had the laws, waterboarding would be fine,'' Trump said. "If they could expand the laws, I would do a lot more than waterboarding. You have to get the information from these people.

Trump added that he believes torture would be effective in obtaining information in a case like this, whereas experts are divided on whether it produces positive or false information.

"I am in the camp where you have to get the information and you have to get it rapidly,'' Trump said.

RELATED: 'Unrealistic' to shut borders, Hillary Clinton says

Trump attributed the turbulence in Brussels to the effects of immigration from the Middle East.

"Belgium is no longer Belgium,'' he said. "Belgium is a horror show right now. This all happened because frankly there's no assimilation. They are not assimilating for whatever reason. They don't want laws that we have, they want Sharia Law, and you say to yourself, at what point, how much of this do you take?

"What we're doing is we're allowing thousands and thousands of these people into our country, and we're going to have nothing but problems, as sure as you're sitting there."

In a phone interview on TODAY Tuesday, Democratic front-runner Hillary Clinton said closing the U.S. borders is "unrealistic" in the wake of the attack. She also opposed using any type of torture methods in trying to obtain information from suspects, saying military leaders have stated that it's not effective.

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