Tokyo (CNN) -- Three Chinese ships entered into waters near small islands in the East China Sea that are claimed by both countries on Friday morning and were staying despite a warning from a Japanese Coast Guard ship, the coast guard said.
The move continues a dispute over the islands -- which Japan calls Senkaku and China calls Diaoyu -- that stretches back decades.
Last week, Japan scrambled fighter jets near the small islands in the East China Sea after a Chinese plane was seen there.
Chinese government ships have repeatedly entered the waters around the remote, rocky islands since the Japanese government announced in September it was buying several of the islands from private owners.
Japanese Coast Guard vessels have engaged in games of cat and mouse with the Chinese ships, with both sides broadcasting messages to one another insisting they have territorial sovereignty over the area.
Analysts say that by sending its own patrols into the area, China is challenging Japan's de facto control of the islands, which has been the status quo for the past 40 years.