Inada justified the decision by saying Japan shared similar concerns with the U.S. about China's rise to power and aggressive pursuit of territorial claims.
Japanese delegates have called on China to resume bilateral talks on an agreement to jointly develop gas fields in the sea.
The Japanese defense minister expressed support for the U.S. Navy's freedom of navigation exercises near disputed islands in the South China Sea, which have drawn ire from Beijing.
Japan will step up its activities in the contested South China Sea through joint training patrols with the United States as well as bilateral and multilateral exercises with other regional navies, said Defence Minister Tomomi Inada on her first official visit to the U.S. early yesterday, as she criticised Beijing's assertive actions in the disputed waterway.
This dual-pronged approach is intended as a check to Beijing's efforts to encroach on Japan's sovereign waterways, while leaving an avenue for discussion once China decides to come to the bargaining table, according to Ms. Inada, who is considered a defense hawk as Japan engages in a major national debate over the future of its constitutionally mandated status as a "pacifist" nation.
The defence minister said she was willing to hold a "constructive dialogue" with Beijing on preventing confrontations between their air and sea forces to ease regional tensions.
In July, an global arbitration court invalidated several of China's territorial claims in the South China Sea in a case brought by the Philippines.
Inada accused China of flouting worldwide norms and said that stability in Asia-Pacific waters is a matter of global importance.
The Philippines will no longer conduct naval patrols in the South China Sea with foreign powers, President Rodrigo Duterte said on Tuesday, September 13.
Inada also said that Chinese incursions in waters surrounding the Senkakus have become "routinized" in recent years, citing an "unprecedented" incident in which Chinese law enforcement ships and fishing boats sailed into Japanese territorial waters surrounding the islands and made multiple incursions over a period of several days.
Carter and Inada exchanged views on building a principled and inclusive security network in the Asia-Pacific region, Cook said, including enhancing trilateral cooperation with South Korea, Australia and India.
The ministers affirmed that the Senkakus fall under the Japan-U.S. security treaty, meaning that the United States will defend Japan in the event of emergencies over the islets.