Associated Press/Mindaugas Kulbis
The New York Times obtained a draft of the executive order and published it on Wednesday.
"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."
McCain cited the National Defense Authorization Act put into place during the Obama administration that "reaffirmed the prohibition on torture by limiting interrogation techniques to those in the Army Field Manual."
McCain also noted the Trump appointees who have said they would support the US legal ban on torture.
"During both our personal conversations and his confirmation hearing, CIA Director Mike Pompeo repeatedly committed to me that he will comply with the law that applies the Army Field Manual's interrogation requirements to all US agencies, including the CIA," McCain said.
"In response to written questions from the Senate Armed Services Committee, Secretary of Defense James Mattis said he 'support[s] using the Army Field Manual as the single standard for all US military interrogations.' I am confident these leaders will be true to their word."
Former CIA Director Michael Hayden predicted last year that the US military would refuse to follow unlawful orders from Trump.