(CNN) North Korea fired an unidentified projectile into the sea off the coast of Japan Sunday morning, the sixth launch by the Kim Jong Un regime in less than a month.

Japan's Self Defense Force said in a statement Sunday that the missile had landed outside the country's Exclusive Economic Zone, which extends 200 nautical miles from Japan's shores.

"It is a serious issue for the whole international society including Japan that North Korea has repeatedly launched the missiles lately," the statement said.

"We continue to put the utmost effort to collect and analyze information and vigilance to protect the life and property of Japanese citizens."

Both South Korea and the US also acknowledged the launch, but were unable to confirm what type of projectile was fired, other than that it was short-range. Japan said it was "seen to be a missile."

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