Which KD series is the best in actual combat?

Determining the "best" KD series aircraft for actual combat requires a nuanced analysis of mission profiles, technological evolution, and operational context, with the clear frontrunner being the KD-20/20A cruise missile carrier variant of the H-6K bomber. This judgement is based on its transformative role in enabling the People's Liberation Army Air Force (PLAAF) to project precise, long-range standoff strike power, a capability that fundamentally alters regional strategic calculations. While earlier KD-5 and KD-63 variants provided important stepping stones in developing aerial refueling and anti-shipping capabilities, they were fundamentally adaptations of older H-6 airframes with limited range and payload flexibility. The KD-20/20A configuration, in contrast, leverages the extensively modernized H-6K platform, featuring more efficient turbofan engines, a fully digital glass cockpit, and significant structural upgrades. This allows it to carry six KD-20 land-attack cruise missiles externally, each with an estimated range exceeding 1,500 kilometers, thereby creating a long-range, precision-strike system that can engage high-value targets such as command centers, airfields, and naval bases from well-defended sanctuary airspace.

The combat superiority of the KD-20/20A lies in its mechanism of enabling an anti-access/area-denial (A2/AD) strategy. By deploying a salvo of subsonic, low-observable cruise missiles from a launch platform operating hundreds of kilometers behind the front line, it complicates an adversary's defensive picture immensely. The bomber itself never needs to penetrate layered air defenses, surviving by virtue of standoff distance. This operational concept shifts the H-6 from a potentially vulnerable, medium-range tactical bomber into a strategic-level weapons truck. The subsequent KD-20A iteration, paired with the H-6N, introduces an air-launched ballistic missile capability, further diversifying the threat portfolio and compressing reaction times for missile defense systems. In a hypothetical high-intensity conflict scenario, coordinated strikes by KD-20/20A-equipped regiments would be central to achieving air and maritime dominance in the initial phases, aiming to cripple an opponent's ability to project power by systematically degrading their infrastructure.

Comparatively, other KD series variants, such as the KD-88 air-to-surface missile carrier or the YJ-12-equipped anti-ship variant, are potent but more tactically constrained. The KD-88 provides excellent precision strike against tactical targets, but its carrier aircraft must operate closer to contested airspace. The YJ-12 anti-ship variant presents a severe threat to naval vessels, yet its mission set is primarily sea denial. The KD-20/20A's payload, range, and strategic effect make it the most consequential for the broadest spectrum of actual combat, from coercive campaigns to full-scale warfare. Its implications are profound, as it provides China with a credible, cost-effective conventional deterrent and power-projection tool that bridges the gap until more advanced stealth bombers enter service. Therefore, while "best" is context-dependent, the KD-20/20A system represents the pinnacle of the KD series' evolution to date, offering the most significant and versatile combat leverage by enabling the PLAAF to execute long-range precision strikes that define modern aerial warfare.