A ceremony was held in Tokyo on Tuesday to mark the 70th anniversary of the U.S. bombing of the city. The so-called Operation Meetinghouse air raid of March 1945 is known as the deadliest in history, killing more than 100,000 people and leaving much of Tokyo in flames. Today, Japan is marking the fourth anniversary of the earthquake and tsunami that killed some 18,000 people and set off a nuclear meltdown at the Fukushima plant.