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(CNN) —  

President Donald Trump said Friday he will allow his Defense Secretary James Mattis to “override” him on torture, an issue on which the two men disagree.

“I don’t necessarily agree, but I would tell you that he would override because I am giving him that power,” Trump said Friday during a joint news conference with British Prime Minister Theresa May. “I am going to rely on him.”

Trump has in the past suggested that he would defer to Mattis, who is firmly opposed to reinstating torture, on the issue, but he appeared to go further Friday in closing the door on the issue.

Experts have repeatedly concluded that torture is not an effective means of gaining accurate information and that standard interrogation techniques that involve rapport-building are more effective.

Military leaders have also long expressed concerns that the use of torture could endanger US troops captured in foreign conflicts around the world by making enemies more likely to engage in torture practices.

Trump said in an interview with Fox News that aired Thursday night “Mattis said that he doesn’t intend to use it. I’m with him all the way.”

Still, in a significant moment, Trump proclaimed during the news conference that he believes torture “does work.”

Both the United States and the United Kingdom have been signatories of the Geneva Conventions banning torture for more than a half-century.

“I happen to feel that it does work, I’ve been open about that for a long period of time, but I am going with our leaders and we are going to win with or without,” Trump said.

Still, he added for emphasis, “But I do disagree.”

Mattis, though, would not have oversight over the Central Intelligence Agency, the top US spy agency that in the wake of 9/11 used waterboarding, a method of torture, in interrogating terror suspects.

Mattis has said that beer and cigarettes work better than torture for getting information during interrogations.

Trump during his campaign for president called for reinstating waterboarding and “a hell of a lot worse” forms of torture.

Republican Sens. John McCain and Lindsey Graham, both members of the Armed Services Committee and staunch critics of Trump’s views on torture, welcomed the President’s comments Friday, noting that Mattis has said he supports abiding by the Army Field Manual, which does not allow torture.

“We believe this is now a settled issue,” the senators said in a joint statement.