Defense Secretary James Mattis "will override because I'm giving him that power," Trump told a joint press conference with British Prime Minister Theresa May. "He is an expert. He is highly respected."
"And he has stated publicly that he does not necessarily believe in torture or waterboarding or however you want to define it - enhanced interrogation I guess would be words that a lot of people would like to use," Trump said, adding that he himself does "not necessarily agree".
Trump's views on torture have raised concerns that he will try to reverse laws put into place by predecessor Barack Obama outlawing the brutal interrogation techniques like waterboarding used by the CIA on suspects following the September 11, 2001 attacks.
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US media earlier this week reported that the Trump administration was drafting a order that would reauthorise the "black site" prisons around the world where US officials subjected suspects allegedly tied to Al-Qaeda to now-illegal "enhanced interrogation techniques."
White House press secretary Sean Spicer denied that the document had originated in the White House.
But in an interview on Wednesday Trump said that torture is effective.
"Do I feel it works? Absolutely, I feel it works," he told ABC News.
During a hearing earlier this month to confirm his position as director of the Central Intelligence Agency, former Congressman Mike Pompeo said he would not back torture and "can't imagine" that he would be asked to do so by Trump.
But he suggested that he could support changing the law, if useful.
"If experts believed current law was an impediment to gathering vital intelligence to protect the country, I would want to understand such impediments and whether any recommendations were appropriate for changing current law," he said.
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