The multipurpose munition (한글: 복합기능탄) has several modes including proximity, air burst, armour-piercing and fragmentation. The mode is configured by the K21's FCS, which then transmits the necessary data to a small programmable fuse system inside the round before it is fired. This allows more control over the trajectory and impact of the round, expanding the scope of possible targets from medium armored vehicles to aircraft and infantry personnel. Anti-tank armament includes an indigenous 3rd-generation ATGM, with performance similar to the Israeli Spike and armour penetration of of RHA base. The fire-control system is able to spot and track targets as far away as away and identify them from up to away. IFF sensors are also present. The vehicle also has hunter-killer capabilities with its separate commander's sight (IFV Commander's Panoramic Sight or ICPS) and gunner's sight (IFV Gunner's Primary Sight or IGPS), which can detect both ground and aerial targets. The sights are designed by Samsung Thales. The gunner's sight is equipped with a third generation thermal viewer and a 1.54 μm laser rangefinder. It can detect targets from 6,000 meters away and identify them from 3,000 meters away. The commander's sight is equipped with the same system as the gunner's. This allows the gunner to use the commander's sight to engage targets if his own sight is disabled or destroyed. The commander of the vehicle also has the ability to override the command to take control of the turret and gun from the gunner. Although not much is known about the composition of the K21's armour, the frontal armour of the vehicle is specifically designed to protect against large caliber automatic cannon rounds, primarily the 30 mm APDS munitions (30×165mm) for 2A72 automatic cannon used on BMP-3, which has approximately armour penetration at ranges of 1,000 m. The side armour is designed to protect against 14.5 mm AP rounds, which has approximately armour penetration at 1,000 m. The top can withstand fragments from 152 mm artillery shells exploding as close as 10 meters. It has been confirmed that the composite armour comprises S2-glass fibre and Al2O3 ceramic including lightweight aluminium alloy. The vehicle has a soft self-sealing fuel tank that can absorb the impact of a projectile. There is also an automatic fire suppression system inside the vehicle to extinguish any internal fires that might erupt.