"I would also hope that he would not want to be associated with a technique which was invented in the Spanish Inquisition, was used by Pol Pot in one of the great eras of genocide in history and is being used on Burmese monks as we speak," the Arizona senator said. "America is a better nation than that."

Waterboarding generally makes breathing difficult and can cause the subject to think he's drowning. It's banned by domestic law and international treaties, but those policies don't cover CIA personnel and President Bush's administration won't say whether it has been allowed against terrorism detainees.

McCain was a prisoner of war for more than five years during the Vietnam War. He was tortured during that time, but said he wasn't subjected to waterboarding.

"If the United States was in another conflict, which could easily happen, with another country, and we have allowed that kind of torture to be inflicted on people we hold captive, then there's nothing to prevent that enemy from also torturing American prisoners," McCain said.