Clearly, they don't live up to the Russian marketing hype, but I doubt they're worthless, either.The US, Israel, and other NATO countries are just very good at figuring out their weaknesses, and developing good tactics to counter them.
If they are being bypassed/countered by their opponents then they are worthless.
They are not even making it difficult for opponents or stalling or anything. They are just sitting there doing nothing (eg Syrian S300) or being destroyed.
Their net contribution to war fighting in Libya and Syria is to divert aircraft/drones to destroy them.
Iraq had one of the most sophisticated, and dense air defense systems on the planet, courtesy of their Soviet/Russian allies, but it was systematically destroyed over time by coalition forces.
Iraq's AD system had a number of weaknesses which meant it was quite weak overall:
- Core C3 system was French KARI system which was compromised the moment France shared its secrets with the Americans. The battle management system was British ASMA which was also compromised from the start.
- Iraqi SAM systems were mainly already old and extremely outdated – SA-2/-3/-6. All 3 systems were obsolete by 1982 when Israel dismantled a large chunk of the Syrian AD system in a single day. The US had already bypassed similar systems over Libya in 1986 Operation El Dorado Canyon.
The only modern SAM system was the Roland.
Iraq had some other issues:
1. Politicised officer corps where promotions were based on tribal and political allegiances and not competence.
2. Totally obsolete fighter arm mainly based around MiG-23 and MiG-25 with nearly 40 MiG-29s supporting them. Even the MiG-29s were third rate.
3. Apparently the system was far more rigid than even the Soviet one due to need for political control.
As such Iraq's supposed sophisticated system never managed to shut down Iranian air ops despite Iran's fleet dwindling due to battle losses, embargo and no new aircraft being received except a small number of smuggled F-5A/Es and some Chinese J-7 (MiG-21 clone).
And it just crumpled when smashed by Uncle Sam and friends.
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Some of these issues are present in Russia and China who uses Russian derivatives (eg HQ-22 is essentially a Chinese copy of the S300).
Note that the S300 also currently serves in NATO (Greece and Bulgaria) so is totally compromised despite upgrades.
Both Russia and China have weak fighter arms.
Excluding pure ground attack aircraft, Russia has only 600 ish combat aircraft capable of air to air (Su-27/30/35/MiG-31.
MiG-29 is only used for training).
China has about 1300 however half of them are J-7s (MiG-21 clone) or J-8 (equivalent to a MiG-23). The rest is split between Flanker derivatives ala Su-27/30/J-11/J-15/J-16 and J-10 (modified version of Israeli Lavi fighter)
They are also short on AWACS – Russia only has 16 A50s, only 4 of which have been substantially upgraded since 1980s.
The Chinese AWAC fleet is about 30 aircraft.
In comparison, NATO operates 57 AWACS aircraft (though numbers have shrunk by about 6 in recent years) not including French and US E-2 Hawkeyes deployed on carriers but including 4 Turkish B737 AEW&C.
US Allies in Pacific (Korea, Australia and Japan) contribute another 27 aircraft.