Armed Chinese Coast Guard ships are reported to have confronted Japanese patrol vessels near the disputed Senkaku Islands in the East China Sea on Saturday.
According to the Japan Times, the incident is said to have taken place to establish China's maritime claims on the disputed territory and waters off its eastern and southeastern coasts.
The new coast guard was formally inaugurated after the resources of four former agencies were merged and vessels from the uninhabited islets were replaced by four armed ships.
The new coast guard has centralized operations, which is nominally under civilian control, but closely coordinates with the Chinese Navy.