The launch of the Nodong missile was only the fourth successful test of the missile since its development in the late 1980s and early 1990s. The launch followed a series of short-range missile and rocket launches along the North Korean coastline and coincided with large-scale U.S. and South Korean joint military exercises. Meanwhile, the United States, South Korea and Japan participated in a leadership summit in Europe — on the sidelines of the Nuclear Security Summit — on the fourth anniversary of the sinking of a South Korean navy corvette, the ChonAn. Just ahead of the Nodong tests, North Korea accused the South of fomenting tensions by scattering anti-North Korean leaflets near the Yellow Sea border. At the same time, Pyongyang criticized Seoul's continued claims that the North was behind the ChonAn sinking, and it warned of potential military action against the South.