China is producing vast undersea maps for submarine warfare, report says

• China is conducting underwater surveys of the Indian Ocean, a report says. 
• They could be to plan submarine warfare, the Center for Strategic and International Studies said.
• It comes as China looks to expand its military reach in the Asia-Pacific region. 

China is mapping vast areas of the Indian Ocean under the guise of civilian research — and it could be to plan submarine warfare, a think tank said.

In a new study, the Center for Strategic and International Studies, or CSIS, think tank said that Chinese vessels carrying out civilian oceanographic-research projects likely collected data for China's People's Liberation Army to help plan potential military operations.