An Iranian nuclear physicist was assassinated today in a bomb blast outside his home in Tehran. Massoud Ali-Mohammadi was a nuclear scientist who taught at Tehran University and who might have had links to Iran’s disputed nuclear program. No one has claimed responsibility for the attack, but Iran’s Foreign Ministry blamed Israeli and American agents. The killing comes one month after Iran accused the United States of kidnapping another Iranian nuclear scientist, Shahram Amiri, who has been missing since June when he traveled to Saudi Arabia on a religious pilgrimage.