premise: He did not say if this structure was manned by Chinese troops.
  One of the vessels as "positively identified" as belonging to the Shuguang 04 class with bow number 427. It was "observed to be accompanied by two small fishing boats and was towing two other boats," Villanueva said.
  Another vessel, with bow number 420, was identified as belonging to the Hai class, Villanueva said but did not give a description of the third vessel.
  "The Department of Foreign Affairs is sending a diplomatic protest to its counterpart in Beijing and will inform its ASEAN counterparts of these developments," Villanueva said.
   What was involved in these developments?
hypothesis: It was "observed