By Joyce Lee and Kantaro Komiya SEOUL/TOKYO (Reuters) -North Korea fired a ballistic missile from a submarine on Saturday, South Korea said, an escalation just before the inauguration of a South Korean president who has vowed to take a hard line against the North and the visit of the U.S. president. South Korean military said North Korea fired what is believed to be a submarine-launched ballistic missile (SLBM) into the sea off its east coast around 0507 GMT on Saturday from near Sinpo, where North Korea keeps submarines as well as equipment for test-firing SLBMs. Japan also said the projectil…