Japan today announced the birth of a new baby island in the south of the nation’s territorial waters.

An undersea eruption off the coast of Nishinoshima island broke the ocean’s surface waters yesterday, sending a plume of smoke and ash about 600 meters (2,000 feet) into the air and alerting the Japanese Coast Guard to the new island’s formation.

PHOTOS: New Japanese Island Forming in Pacific Ocean

The cinder cone emerging from the ocean is suspected to be part of the same volcanic system that enlarged Nishinoshima in 1974 and has formed an islet on Nishinoshima’s southeast side that’s about 150 meters (about 500 feet) in diameter. The last time Nishinoshima showed any volcanic activity was in January 2000, when an eruption on the island’s northwest side discolored the water a pale yellow-green.

“Japan’s top government spokesman joked that he hoped the outcrop would mark an expansion of Tokyo’s maritime territory — a reference to diplomatic rows with China and South Korea over ownership of other islands far from the tiny islet,” reported the AFP.

“If this becomes a solid island, our country’s territorial waters will expand,” quipped Chief Cabinet Secretary Yoshihide Suga. The most recent volcanically formed islands in Japan’s waters have remained uninhabited or have eroded back into the ocean. This one may do the same or continue to enlarge the size of Nishinoshima.

IMAGE: A volcanic eruption in southern Japan gives birth to a new islet. (Japan Coast Guard)