New Delhi, July 9 -- Japan raised strong caution against China's rapid acceleration of military activity in extensive areas from its southwestern coasts to the Pacific, describing the moves as the biggest strategic challenge.

China's growing joint operations with Russia also pose serious security concerns to Japan, along with increasing tension around Taiwan and threats coming from North Korea, the Defense Ministry said in an annual military report submitted to Cabinet on Tuesday.

"The international society is in a new crisis era as it faces the biggest challenges since the end of World War II," the report said, citing significant changes to the global power balance while raising concerns about an escalation of the China-U.S. rivalry. ...