China did not deny it saying their “vessels for marine research did sail across relevant waters to the northeast of Luzon, the Philippines last year, exercising navigation freedoms and the right to innocent passage only, without conducting any other activities or operations.” Concern over the presence of Chinese ships in Benham Rise turned into shock when President Duterte said he had given the Chinese permission to conduct a survey in Benham Rise. But no one really knew what kind of survey the Chinese ships did.

Tordesillas, E. (2017, April 3). What the Chinese ship did in Benham Rise. Malaya Business. Insight, p. B4.