Updated

Former Vice President Dick Cheney says he had a secret resignation letter signed and stored in a safe for most of the Bush administration in case he became incapacitated.

Cheney says he signed the resignation letter in March 2001, just about two months after taking office. He says only President George W. Bush and one of the vice president's staff members knew the letter existed.

Cheney says one of the reasons for having a resignation letter on hand was his history of health problems, including multiple heart attacks. He says the letter could have been used if he had been incapacitated by a heart attack or stroke.

Cheney discussed the secret letter in an interview with NBC News to promote the release of his memoir.