In the wake of the Brussels attacks, Donald Trump did not let the opportunity slip past to rehash two of his more contentious arguments: to be very tough on the borders for those entering the United States - particularly the Muslim people, and to allow torture during terrorist interrogation.

Trump Urges Americans to be More Vigilant and Smart

"Look at Brussels. Brussels was a beautiful city, a beautiful place... Now it's a disaster city, a total disaster," Trump said on Tuesday. "We have to be very careful in the U.S. We have to be very, very vigilant as to who we let into this country."

Trump said that he has come to know Brussels as one of the finest, most beautiful and safest cities in the world, but it has deteriorated in recent years. It has become a "catastrophic" and "very dangerous city. He said that Brussels today is a total mess. He doesn't want the United States to follow suit and that is why he is asking Americans to be more vigilant and smart.

The GOP frontrunner also reiterated the need to use whatever means possible in order to gain necessary information from terrorists in custody like Salah Abdeslam, who is a suspect in the Paris attacks. "Waterboarding would be fine, and if they could expand the laws, I would do a lot more than waterboarding," he said. "I am in the camp where you have to get the information and you have to get it rapidly."

The Presidential Candidates' Also React to Brussels

Trump's rivals for The GOP nomination also weighed in on the Brussels attack. Ted Cruz highlighted that the incident is not just an isolated one, but signifies a war against radical Islamic terrorism. John Kasich, meanwhile, said, "I would have talked more about the battle against the civilized world, clearly I would be coming back home to gather the leaders, the heads of state, and put together teams of people to figure out why we have these vulnerabilities."

Hillary Clinton offered her thoughts and prayers to the people of Belgium, particularly those who had been killed and injured in the attack. She also expressed her optimism that the terrorists behind the attack won't succeed in trying to subvert the "democratic values" of the people.

Bernie Sanders, on the other hand, called the act "barbaric" and also expressed his deepest condolences to the victims and their families, as well as the local residents from the city.