"I love this photo @harleyweir took of me," Kristin said alongside the picture on Instagram. "All this discussion about it makes me think about how alienated and scared some people are to the female human body. Be and love yourself and your sexuality #girlpower."
It's by no means the first time that Calvin Klein has courted controversy with an ad. The brand's pictures of a then-15-year-old Brook Shields asking: "You wanna know what comes between me and my Calvins? Nothing" caused a media storm in 1981, and saw the brand accused of sexualising a child. Pictures of Kate Moss topless astride Mark Wahlberg drew similar criticism in 1992, despite the fact that she was 18, and later naked images of Eva Mendes and Jamie Dornan garnered worldwide attention.