The Dongguan, a Type 053H1G frigate of the People's Liberation Army Navy, was followed and monitored by an unidentified aircraft during its patrol mission over the disputed South China Sea on June 19, reports the PLA Daily, the official newspaper of China's armed forces.

Sun Qihu, the captain of the Dongguan, told the paper that an unidentified vessel was detected first in the morning of June 19 in the patrol area. After spotting the Dongguan, the unidentified vessel turned back and left the region. However, an unidentified aircraft then appeared on Dongguan's radar screen.

The PLA Daily reported that such incidents occur not only in the South China Sea, but in every other contested maritime region. On the same day, a fighter of PLA Navy's East Sea Fleet was dispatched to patrol China's Air Defense Identification Zone (ADIZ) to prevent foreign aircraft from intruding in Chinese airspace, the paper said. Meanwhile, the PLA Navy recently dispatched the Mianyang and Huludao, two Type 053H1G frigates from the North Sea Fleet, to patrol over the waters of the Western Pacific with the support of the Hongzehu supply ship.

Because of the constant threat of unidentified and hostile aircraft or vessels entering Chinese airpace or waters, the PLA Daily stressed the importance of the coordination between the PLA warships and aircraft. The paper added that PLA aircraft and warships are capable of conducting patrol missions several hundred times a year. Between 2012 and 2013, Chinese warships conducted around 66 patrol missions in the open sea.