Ashton Kutcher is smoking again, 18 months after vowing to kick his nicotine habit. In late 2006, the actor boasted to U.S. chat show host Jay Leno that he had quit smoking and would stay cigarette-free. But he has now been photographed lighting up during a break from filming new movie Spread. A friend tells U.S. tabloid Star, "Aston really thought he had smoked his last cigarette, but they are incredibly addictive. It's tough when everyone on the set is smoking in your face."