Jane Fonda (search) says her 1972 visit to a North Vietnamese anti-aircraft gun site, an incident that brought her the nickname "Hanoi Jane," (search) was a "betrayal" of American forces and of the "country that gave me privilege."

"The image of Jane Fonda, 'Barbarella,' Henry Fonda's daughter ... sitting on an enemy aircraft gun was a betrayal ... the largest lapse of judgment that I can even imagine," Fonda told Leslie Stahl in a "60 Minutes" interview that will air Sunday night.

Fonda, whose memoir "Jane Fonda: My Life So Far" (search) comes out next week, said she did not regret meeting with American POWs in North Vietnam or making broadcasts on Radio Hanoi.

"Our government was lying to us and men were dying because of it, and I felt I had to do anything that I could to expose the lies and help end the war," she said.

Also on "60 Minutes," Fonda acknowledged that she had participated in sexual threesomes, at the encouragement of her first husband, French film director Roger Vadim (search).

She said she consented because, "I felt that if I said no, that he would leave me and I couldn't imagine myself without him."