Spokesperson Hua Chunying (file photo)

BEIJING, June 4 -- China on Sunday expressed strong dissatisfaction with and firm opposition to "irresponsible remarks" made by the U.S. Secretary of Defense James Mattis and Japanese Defense Minister Tomomi Inada on the South China Sea and Taiwan issues during the just concluded Shangri-La Dialogue.

Stressing China has indisputable sovereignty over the Nansha islands and their adjacent waters, spokesperson Hua Chunying said China has always been committed to peacefully solving disputes through consultation and negotiation with countries directly concerned.

China has always respected and maintained the freedom of navigation and overflight in the South China Sea in accordance with international law. Meanwhile, China firmly opposes certain countries' sabre-rattling in the region under the excuse of that freedom, which threatens China's sovereignty and security, Hua said.

China's construction projects on the Nansha islands are aimed at improving working and living conditions of staff there while better fulfilling its international obligations, Hua said.

She said necessary defense facilities built in a sovereign state's territory represents its self-protection and self-defense rights, and has nothing to do with the so-called "militarization".

The situation in the South China Sea has improved and shown positive development momentum, Hua said, citing the success of the first meeting of the China-Philippines bilateral consultation mechanism, and the agreement between China and ASEAN countries on the framework for the Code of Conduct (COC) in the South China Sea.

Hua said China hopes relevant parties will fully respect efforts made by countries in the region and play a constructive role in maintaining peace and stability in the South China Sea.

Regarding the Diaoyu Island issue, Hua said the island and its adjacent islets have been part of China since ancient times, so it is legal and justified for the Chinese official ships to patrol and conduct law-enforcement activities in relevant waters.

"China is firmly determined to safeguard its territorial sovereignty and maritime rights," Hua said, adding that the country's patrol and law-enforcement activities will continue.

Calling the Japanese side's remarks "running counter to the fact" and "not worth mentioning", Hua said China urges Japan to make constructive efforts to ameliorate China-Japan ties.

Talking about the Taiwan issue, Hua stressed China's position has been "clear and coherent".

She said China has always opposed the so-called "Taiwan Relations Act," which was unilaterally formulated by the United States, and asked the United States to abide by the one-China policy and principles enshrined in the three joint communiques.

China urges the United States to stop selling arms to Taiwan and terminate any official exchanges so as to guarantee the development of bilateral relations.

Hua also reaffirmed China's "clear and coherent" position on the Terminal High Altitude Area Defense (THAAD) issue, urging relevant countries to immediately stop the deployment of THAAD.