Two Chinese government ships sailed into disputed waters off Japan-administered islands in the East China Sea Monday, the Japanese coastguard said, as Tokyo prepared to strengthen its military posture.
The two vessels were sailing in territorial waters extending 12 nautical miles around one of the Senkaku islands, which China also claims and calls the Diaoyus, as of 10:30 am (0130 GMT).
Since Tokyo nationalized some of the islands in September 2012, Chinese vessels and aircraft have regularly approached them, playing cat and mouse with the Japanese coastguard.
Earlier this month Japan summoned the Chinese ambassador, as the two sides traded accusations of blame for a near-miss involving fighter jets over the East China Sea.
It was the second time in less than three weeks that Tokyo had accused Beijing of playing chicken in the skies near the hotly contested islands.
In recent months China has also intensified its activity in the South China Sea, which it claims almost in its entirety.
The incident comes as Prime Minister Shinzo Abe pushes ahead with a controversial plan to loosen the constraints on Japan’s military and allow it to fight in defense of an ally, something currently banned under the pacifist constitution.
Beijing has repeatedly warned of what it says is the danger of Japan “remilitarizing” under Abe, and regularly lambasts Tokyo for its apparent lack of repentance for past misdeeds.