Former President Jimmy Carter signed hundreds of copies of his latest book Monday at a Portland appearance at Powell's Books.
Carter served one term as president from 1977 to 1981. He lost re-election to Ronald Reagan, at least in part because he had been unable to free American hostages held in Iran for 444 days. Carter praised a recent nuclear agreement with Iran in comments to reporters.
"I have complete confidence in it," Carter said. "I believe it's good for Iran, good for the United States, good for the world. Good for Israel. And I have complete confidence in (Secretary of State) John Kerry. I've known him for many years. If he says it's binding, and that Iran will be punished if they violate it, I believe him."
The deal would relieve some economic sanctions on Iran in exchange for greater monitoring of the country's nuclear programs. But opponents of the deal have criticized it because they say it wouldn't fully dismantle Iran's nuclear development.
Carter is 90 years old and travels frequently as an author and on behalf of the nonprofit Carter Center that he founded with his wife Rosalynn in 1982.
The former president also spoke in support of President Obama's trip to Africa — where the Carter Center works on improving health. He suggested Obama might better be able to prioritize helping Africa after his presidential term ends.