North Korea fired another unidentified projectile into the sea off the coast of Japan Sunday morning, marking the sixth such launch in less than a month. Japan’s Defense Force confirmed the launch on Sunday, backed up by the U.S. and South Korea. “It is a serious issue for the whole international society including Japan that North Korea has repeatedly launched the missiles lately,” Japan said in a statement. “We continue to put the utmost effort to collect and analyze information and vigilance to protect the life and property of Japanese citizens.” The projectile is thought to be a short-range missile. North Korea launched three projectiles on March 9th and two others on March 21.