If ur talking AIR defence network without airforce.Russia,massive,modern,diverse.
Then china i agree with 500.USA don't need air defence because its always on the offensive with its air force instead.
- First understanding: Ground air defense is essentially a short term solution to a long term problem.
- Second understanding: No one ever win a shooting war by being on the defensive.
The long term problem here is the conflict under which ground air defense is an element. The goal of any shooting war, from here on shortened to simply 'war' for sake of brevity, is to deny the enemy the capabilities to wage war and the only solution of that problem is to take the war to enemy home soil and that require another element: offensive air operations.
Since the posture of ground air defense is naturally permanently defensive but if there is no companion offensive air policy, the absence of offensive air inevitably would make the overall posture of the war persistently defensive, then even though the enemy will require respite periods in order to restock his offensive air resources, he will do so with the understanding that if his capability to rearm is faster than yours, he will eventually outpace your defenses and will achieve
THE goal: the denial of the enemy's capabilities to wage war.
In his perspective, the enemy is you.
A perfect example of this is the Vietnam War. Put aside the political rhetoric on how the US 'lost' that war and focus on the technical aspects of that war. North Vietnam's ground air defense capabilities were formidable enough that only a superpower, the US, is capable of going against such a defense. But the problem for the North Vietnamese is that they were incapable of any offensive air policy, not even against South Vietnam, of which basing was available for US offensive air. Of course, North Vietnam could not conduct any offensive air against US home soil. US offensive air power attacked North Vietnam's industrial base at will. It was only political respite periods successfully pleaded by North Vietnam that allowed rearming. If the US was not convinced of North Vietnam's (repeated) plead for partitioned peace, US offensive air would definitely overwhelmed any Soviet-China resupply of ground air defense resources to North Vietnam.
No different with Desert Storm but in this war, the US-led alliance decidedly refused to apply the incrementalism of offensive air policy from the Vietnam War and prosecuted offensive air to the fullest capabilities. The US-led alliance conducted not just offensive air operations, which is the physical realm, but also as much as technology allowed in the EM spectrum, blinding the Iraq ground air defense system of tactically important sensors necessary for coordination between leadership and discrete units.
It is not true that the US does not need ground air defense capabilities, we do. But we do so with the 2nd understanding. Offensive air policy give US the respite periods we need to rearm and reinforce our defensive methods, if necessary, while at the same time harass or even destroy the enemy his capabilities to wage war.