Japan ramped up its criticism of China's land reclamation and offshore platforms in disputed seas on Tuesday in a hastily revised annual defence report.
The 500-page white paper, approved by Prime Minister Shinzo Abe's government, for the first time includes satellite images of Chinese man-made islands in the South China Sea.
China claims most of the 3.5 million sq km (1.35 million sq mile) South China Sea, with the Philippines, Vietnam, Malaysia, Brunei and Taiwan also staking claims.
Japan has no claim in the South China Sea but is in dispute with China over small islands in the East China Sea.
After hawkish members of Abe's party complained that the report was too soft on China, the Defence Ministry appended a demand for China to halt construction of platforms in the East China Sea that it began two years ago.
"We have confirmed that China has started construction of new ocean (exploration) platforms and we repeat our opposition to unilateral development by China and call for a halt," the ministry said.
The paper outlining Japan's defence posture and perceived threats comes after its lower house of parliament last week passed legislation that for the first time since World War Two would allow Japanese soldiers to fight overseas.
China said the legislation called into question Japan's post-war commitment to "the path of peaceful development".
Japan's complaints about platforms that Japan fears could be used as radar outposts in the East China Sea come as Japan is playing a more prominent role in the South China Sea dispute.
Japan has angered China with criticism of artificial islands that China is building in the Spratlys Islands.
Japan fears Chinese military bases in the South China Sea could bolster its influence over a region through which US$5 trillion in trade passes every year, much of it to and from Japan.
China has said its constructions in the South China Sea would be used for defence as well as to provide civilian services that will benefit other countries.
Japan is seeking to build ties in Southeast Asia that it hopes will improve the capacity of countries there to keep tabs on Chinese activity.
Japan and the Philippines have conducted two joint naval exercises in and around the South China Sea and in June, Abe and Philippine President Benigno Aquino said they would begin talks that could led to Japan using Philippine bases.
Japan has also said it may begin air patrols in the South China Sea. China said it would see that as interference.