SEOUL—North Korea fired two short-range missiles into the sea early Monday, an apparent protest at the start of major military drills involving U.S. troops in South Korea.

North Korea fired two suspected Scud ballistic missiles between 6:32 a.m. and 6:41 a.m. local time, South Korea’s Defense Ministry said. They flew east from Nampho, a port south of Pyongyang, and landed in the sea about 490 kilometers (304 miles) away, the ministry said.

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