Derived from jujitsu and Japanese sword arts like aikijujutsu and kendo, aikido was founded by Morihei Uyeshiba in 1942. In addition to combining the old with the new, Uyeshiba focused on techniques that evaded and redirected an opponent’s attack and energy (ki), which means that the majority of aikido techniques focus on joint locks or throws. Because of this ethos, aikido is popular among law-enforcement officers in Japan because they can subdue aggressors without injuring them. In addition to empty-hand techniques, aikido practitioners may train with a weapon, such as a staff, knife or wooden sword. Because of its nonviolent nature, aikido is also considered a very philosophical martial art.