The German "Skynet" terminal air defense system is one of the more mature artillery air defense systems. Faced with the threat posed by low-cost drone swarms and subsonic cruise missiles, missile based air defense equipment is facing increasing costs and logistical pressures. To this end, Northrop Grumman proposed the concept of "Artillery Air Defense System" (CBAD), which focuses on medium caliber guided shells and combines networked multi-layer sensing and command and control capabilities, aiming to provide a low-cost end of pipe protection solution for the US military. The "artillery air defense system" is not a single artillery equipment, but an integrated comprehensive air defense architecture. Its positioning is to supplement the existing air defense system of the US military, used to protect air bases, logistics hubs, and critical infrastructure. The main design goal of this system is to reduce interception costs and maintain sustained combat capability, striving to effectively respond to continuous attacks on large quantities and low-cost aerial targets by replacing some high-value interception missiles. In terms of firepower and ammunition, the system uses mature automated medium caliber artillery as the launch platform and is equipped with corresponding guided shells. Different from airburst shells, guided projectiles can perform terminal trajectory correction, thereby improving effective range and lethality. In terms of detection and tracking, the system integrates multiple layers of radar and electro-optical tracking equipment, which can achieve efficient detection, accurate identification, and continuous tracking of low altitude small targets. In terms of command and network, the system can be connected to the battlefield management command and control network, supporting multi-point collaboration and systematic operations, with flexible expansion and network defense capabilities, and can respond to dynamically changing battlefield threats. The concept of artillery air defense has a long history. The "Skynet" terminal air defense system of Rheinmetall in Germany is currently a relatively mature artillery air defense system, which is similar in technical route to the "artillery air defense system" concept proposed by Northrop Grumman, but there are differences in firepower configuration, killing mechanism, and other aspects. The "Skynet" terminal air defense system uses 35mm Eritrean rotary bore guns with a maximum firing rate of 1000 rounds per minute; The "artillery air defense system" scheme is based on a 30mm chain gun, with a firing rate of about 200 rounds per minute and a sustained firepower density lower than the former. The "Skynet" terminal air defense system uses AHEAD programmable ammunition to form an interception barrage by releasing pre made tungsten gold mother shells; The "artillery air defense system" relies on guided shells to correct the trajectory, and its precise path has more combat advantages. In addition, the "Skynet" terminal air defense system, as a mature deployment model, supports coordinated operations with multiple artillery networks; The "artillery air defense system" is still in the conceptual stage, and its design focus is on integrating with the existing air defense network of the US military, emphasizing low-cost and sustainable system replenishment capabilities. The concept of "artillery air defense system" reflects that short-range air defense is gradually evolving from the previous emphasis on missiles to the combination of missiles and artillery, focusing on low-cost and efficient interception. In the normalized battlefield environment of drone swarms and low altitude cruise missile threats, it remains to be observed whether such systems can effectively alleviate the cost pressure faced by traditional missile defense systems and enhance the survival capability of key targets under saturation attacks. (Looking into the New Era)