Things keep heating up between the U.S. and Iran. On Wednesday, Iran's foreign minister blamed the United States for the disappearance of an Iranian scientist allegedly involved in the country's nuclear program. The scientist, Shahram Amiri, disappeared while making a pilgrimage to Saudi Arabia four months ago. "We hold Saudi Arabia responsible for Shahram Amiri's situation and consider the U.S. to be involved in his arrest," the Iranian minister said. An American official denied any knowledge of Amiri or his disappearance.