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South Korea tests ballistic missile amid fears of North Korea’s growing arsenal

South Korea successfully tested a submarine-launched ballistic missile on the same day as North Korea fired a pair of ballistic missiles off its east coast, breaching U.N. sanctions and ratcheting up tension on the Korean Peninsula. South Korean President Moon said that the planned test was not in response to the North's launches, but also cited the North Korea's nuclear capabilities as a reason for South Korea to develop better missiles.