Story highlights

The incident took place in an already-tense region

Both the U.S. and Japan have expressed concern

CNN  — 

A Chinese ship was “shadowing” a U.S. aircraft carrier in the western Pacific on Wednesday, a U.S. official told CNN.

The incident took place as the USS John C. Stennis was sailing to join warships from Japan and India as part of annual maritime exercises conducted by those nations.

“There is a Chinese vessel about seven to ten miles away,” Reuters quoted Captain Gregory C. Huffman of the Stennis telling reporters aboard the ship. The Chinese vessel had followed the U.S. ship from the South China Sea, Reuters reported.

U.S. defense officials said this type of incident has become routine as China continues to express ire over what it views as U.S. provocations when sailing its vessels near Chinese man-made islands in the South China Sea that China considers its territory.

The United States maintains its maritime patrols in the area are to protect freedom of navigation.

Pentagon officials have expressed concern in recent weeks over China’s posture in the region after U.S. military aircraft encountered multiple close intercepts by Chinese military jets in the skies over the South China Sea.

Japan also expressed its own concerns over China’s naval activity Wednesday after a Chinese Dondiao-class spy ship was spotted by a Japanese surveillance plane in Japanese territorial waters.

“In the wake of the latest Chinese navy ship entry to the contiguous zone of Senkaku islands, [the] Chinese navy’s spy ship entered our territorial water. We have communicated our concern [to China] over the Chinese military operation as whole,” Japan’s Deputy Chief Cabinet Secretary Hiroshige Sekou told reporters at a press conference Wednesday.