North Korea fired two cruise missiles toward the Yellow Sea on Wednesday, Yonhap News Agency reported, citing a South Korean military official.

The missiles were launched from a central region of the nation as U.S. and South Korean troops on Tuesday began a preliminary drill ahead of their annual exercises from next Monday.

The South Korean military detected the missiles fired from the Onchon area of South Pyongan Province in the morning, the official was quoted as saying on condition of anonymity.

The last North Korean cruise missile launch was detected in January. There has been no confirmation of a ballistic missile launch from the North since early June.

Cruise missiles differ from ballistic missiles and as such do not fall under U.N. Security Council resolutions that ban North Korea from ballistic missile activity.

Cruise missiles can travel at a low altitude, making them difficult to detect and potentially troublesome for the South and Japan.

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