Passage: The complete weapon system is called A-213-Vympel-A, which comprises the AK-630M Gun Mount, MR-123-02 Fire Control Radar System, and SP-521 Electrical-Optical Tracker. A single MR-123 radar system can simultaneously control two guns, either two 30 mm gun mounts, or two 57 mm gun mounts, or one 30 mm gun and one 57 mm gun.  The radar system can engage aerial and surface targets at 4 km and 5 km respectively.  The electro-optical system can detect a MiG-21–sized aerial target 7 km away, while torpedo boat–sized surface targets can be detected at a range of up to 70 km.  Features include surveillance and tracking modes, high jamming immunity, laser range finder and TV optical sight. It is in operation on almost all Russian Navy ships from fast attack boats to the Kirov battlecruiser.

Question: What kind of targets can the radar system engage?
aerial and surface targets