An octagonal tower with a conical feature at its top, located on the northeast side of Subi Reef was nearly complete measuring 40 feet on each side and 90 to 100 feet tall in this Center for Strategic and International Studies (CSIS) Asia Maritime Transparency Initiative January 8, 2016 satellite file image released to Reuters on January 15, 2016. REUTERS/CSIS Asia Maritime Transparency Initiative/Digital Globe/Handout via Reuters/Files

An octagonal tower with a conical feature at its top, located on the northeast side of Subi Reef was nearly complete measuring 40 feet on each side and 90 to 100 feet tall in this Center for Strategic and International Studies (CSIS) Asia Maritime Transparency Initiative January 8, 2016 satellite file image released to Reuters on January 15, 2016. REUTERS/CSIS Asia Maritime Transparency Initiative/Digital Globe/Handout via Reuters/Files

An octagonal tower with a conical feature at its top, located on the northeast side of Subi Reef was nearly complete measuring 40 feet on each side and 90 to 100 feet tall in this Center for Strategic and International Studies (CSIS) Asia Maritime Transparency Initiative January 8, 2016 satellite file image released to Reuters on January 15, 2016. REUTERS/CSIS Asia Maritime Transparency Initiative/Digital Globe/Handout via Reuters/Files

June 5, 2016 11:54 PM (UTC+8)