Trump 'absolutely' believes in using torture against suspected terrorists

US President Donald Trump has gone against the views of his Defense Secretary James Mattis by insisting that he believes "absolutely" in the use of torture to gain intelligence.

Trump previously vowed to attack and limit the influence of the so-called Islamic State and other radical Islamic terrorist groups, and during one of his first interviews as President he said that he would support the use of waterboarding and other enhanced interrogation techniques.

Mattis opposes enhanced interrogation, as does CIA director Mike Pompeo, but the latter has said that he would consider sanctioning the practice in certain circumstances.

"When ISIS is doing things that no one has ever heard of, since medieval times, would I feel strongly about waterboarding?" Trump said in the interview with ABC News. "As far as I'm concerned, we have to fight fire with fire."

Trump argued that the US must respond adequately to the tactics used by groups such as ISIS, by loosening restrictions in order to level the playing field.

"We're not playing on an even field," Trump said. "I want to do everything within the bounds of what you're allowed to do legally. But do I feel it works? Absolutely, I feel it works."

Such intelligence tactics were employed by the Bush administration following the terrorist attacks of 11 September 2001, but the reintroduction the practice has been shot down by lawmakers on both sides of the aisle.

The Senate voted unanimously to ban torture emanating from the US government in 2015. Former presidential nominee John McCain was one of those opposed, having ben tortured himself during the Vietnam War.

"The President can sign whatever executive orders he likes," McCain said in a statement. "But the law is the law. We are not bringing back torture in the United States of America."