Remember the threat from North Korea? Pyongyang certainly doesn’t want you to forget: the country fired a short-range missile on Sunday—one day after launching three of these missiles. United Nations Secretary-General Ban Ki-moon has expressed concern about North Korea’s use of short-range missiles, and called Saturday’s launch “provocative action.” Tensions remain high on the Korean peninsula, especially after South Korea pulled all of its workers from an industrial zone earlier this month, following a similar action by the North.