China has sent fleets of fishing vessels and aircraft and ships of its "State Oceanic Administration" to the area.
Japan has a response:
UPDATE: It should be note this plan has been in works for a couple of years, as seen here:
***The government of Prime Minister Naoto Kan has since vowed to beef up defenses for Japan’s “outlying islands,” and it appears close to a decision on the small Yonaguni garrison, a plan that has been under discussion for years.***
China's "patrols" of the disputed area have included warships:
A flotilla of the People's Liberation Army (PLA) Navy patrolled waters near the Diaoyu Islands on Monday after returning from a training exercise in the west Pacific.
The patrol marked the first time for China to confirm its naval operations in the waters near the Diaoyu Islands on the very day when the Navy warships conducted such patrol.
The flotilla, consisting of the DDG-136 Hangzhou and DDG-139 Ningbo destroyers, as well as the two frigates FFG-525 Ma'anshan and FFG-529 Zhoushan from the Navy's Donghai Fleet, passed through the Miyako Strait and entered the West Pacific for a routine training exercise on Nov. 28.
After finishing a series of training operations, the flotilla sailed through a strait near the Yonaguni and Iriomote Islands and arrived in waters surrounding the Diaoyu Islands Monday morning.