After the Japanese bombed Pearl Harbor and declared war on the United States, the Americans partnered with the Chinese to fight against the Japanese Empire. The Chinese lacked weapons and explosives. The explosive flour was packaged in regular flour bags and could be smuggled past Japanese checkpoints to the Chinese resistance fighters. If the smuggler was caught with the explosive flour, he could whip up some not-so-tasty muffins and eat one in front of the Japanese soldier. No one would suspect that the flour was an explosive until later when the smuggler began to vomit. Modifications were made to the chemical composition of the explosive to make it less toxic. It would never be good for anyone to eat a whole loaf of explosive bread, but at least it was less gut-wrenching. The exploding muffins were a success and during Second World War, 15 tons of the explosive flour was smuggled into China and used to fight the Japanese.