Taipei, April 21 -- A Chinese cruise ship sailed within just two nautical miles (3.7km) of Taiwan's Hengchun Peninsula this week, prompting concern from observers and authorities about a possible "gray zone" tactic by Beijing, Taipei Times reported.

The incident was reported by Taiwan ADIZ, a civilian Facebook group that monitors Chinese military activity near Taiwan, which posted footage showing the vessel clearly visible from the shoreline in Pingtung County.

The ship was identified as the Gulangyu, a Bermuda-registered cruise vessel with a capacity of up to 1,800 passengers. Taiwan ADIZ noted that if fully occupied, the number of people on board would be roughly equivalent to a battalion-sized military unit.

"If such events become r...