MELBOURNE, Australia — China has officially commissioned the Chengdu J-20 stealth fighter into service, the country’s defense ministry has announced.

Wu Qian, a spokesperson for the country’s Ministry of National Defense, also said in a media conference on Thursday that flight tests are being conducted as scheduled. The type is currently in low rate production for China’s People’s Liberation Army Air Force, or PLAAF, with at least six examples known to be undergoing operational testing since late 2016 with the service’s 176th Air Brigade at Dingxin Airbase in China’s Gansu Province.

The J-20 is classified by the PLAAF as a fourth-generation — broadly equivalent to fifth-generation in the West — medium- and long-range fighter jet with stealthy characteristics, although these are mainly confined to the frontal aspect of the design.

A recent evaluation of the J-20’s radar cross section, or RCS, by Taiwan’s National Chung-Shan Institute of Science and Technology’s Electronics Systems Research Division seemed to agree with this assessment. But that evaluation was only done on the basic shape of the J-20 as part of a study on large phased array radars and did not factor in other RCS reduction measures, like the use of radar-absorbing paint or materials.

PLAAF J-20 pilots have also confirmed that the type has been built with a level of sensor fusion, although exact details are unknown. Stores are carried internally on the J-20 to preserve the type’s stealthy characteristics, with the main weapons bay capable of carrying up to six PL-12 beyond visual range air-to-air missiles and a smaller weapons bay on each side of the fuselage mounting a single short-range air-to-air missile.