Two J-10 fighter jets attached to an aviation brigade of the air force under the PLA Southern Theater Command take off simultaneously for a training sortie on June 6, 2019. (Photo: eng.chinamil.com.cn)

At least four J-10 fighter jets have been deployed on Yongxing Island in the South China Sea, a satellite image shows, which a Chinese expert said is a necessary move for the country's national defense. 

The image, released by CNN, was taken on Wednesday and represents the first time for J-10s to be seen on the island, according to Israel-based firm ImageSat International.

Fu Qianshao, a Chinese air defense expert, told the Global Times that China has the right to deploy the fighter jets wherever it wants within its territory. 

"The Chinese People's Liberation Army needs to deploy fighter jets at military airports to protect the territorial airspace and sea," Fu said. "This is normal."

Yongxing Island is part of the Xisha Islands in the South China Sea, where the US often sails its military ships under the guise of freedom of navigation, violating China's sovereignty and disturbing regional peace and stability.

Peter Layton, a former Royal Australian Air Force officer and fellow at the Griffith Asia Institute, told CNN that "It could be an early training deployment as part of getting the J-10 squadron operationally ready for an ADIZ (air defense identification zone) declaration."

The Global Times learned that China never confirmed that it may set up an ADIZ in the South China Sea, and there has been no indication of such. 

"There is a massive difference between training and maintenance on land and on the islands. And China needs the jets to protect the peace and stability in the South China Sea," Fu said.