[sudosysgen]

Because neither Russia nor China are planning to use their stealth aircraft over the airspace of another superpower. Good luck fitting a meter-wave AESA on an aircraft.

Beyond that, neither Russia nor China are trading-off anywhere near as much as the US for stealth. Both of their designs are less stealthy but carry better weapons over a longer range with better kinematics at a lower cost.

[SubjectToChange]

Why does it matter whether you are over another superpower's land? As you said, these systems are deployed in Syria and anywhere else. Besides, China is certainly designing their planes to be able to fight to US navy. The fact of the matter is that if a country can afford it, they design stealth aircraft.

[labcomputer]

> Why does it matter whether you are over another superpower's land?

One of the fairly easy ways to defeat stealth is by operating your radar at a low frequency. As the wavelength becomes "much longer" than any characteristic dimension of the airplane, the shape of the airplane matters less and less and the wave will penetrate deeper and deeper layers of radar absorption material.

But there's no such thing as a free lunch.

The problem is that the resolution of your radar depends on the physical size of your antenna relative to the wavelength (either the diameter of the dish, or the spacing of the antenna elements in a multi-static or phased array). So low frequency = long wavelength = bad resolution. You know a plane is in your airspace, but not where in your airspace.

You can solve the resolution problem by installing a physically large antenna. The size of the antenna should be several times longer than the wavelength. That might mean having a single very large dish or it might mean coherent transmitters located hundreds or thousands of meters apart. Great, now we have defeated stealth and have high resolution.

But remember how we were talking about wavelengths much longer than the airplane? How do you carry an antenna that is several times longer than the wavelength for a wavelength that is several times longer than your airplane? I can think of one way: trail wires behind you--but that turns you into a flying bullseye. You might as well file a flight plan.

That creates an asymmetry: It's much easier for the side on the ground to get a good picture of what is going on in the air.

[sudosysgen]

The systems are not fully deployed in Syria. Israel routinely flies F-16s in Syria without much of an issue.

They are in Syria in a pure intelligence capacity.

Beyond Russia and China (and possibly Venezuela), there are no fully operational VHF capable air defence systems

It's also incorrect to consider stealth as a yes/no. It's not a yes/no. It's a sliding scale with tradeoffs. Clearly China and Russia judged stealth to be much less important than the US did.

The USSR could definitely afford stealth aircraft and had all the necessary technology to make it before the US, yet they didn't, and for a reason.

As far as fighting the US Navy, the Chinese doctrine against the USN doesn't involve Chinese airplanes getting within VHF radar range of American large surface vessels before a crippling blow is already delivered.

[SubjectToChange]

The point about Syria is that if Russia and China want to fly over _any_ other country then they must assume that they will encounter VHF radar. And if VHF radar does render stealth technology useless then any include it at all in their designs? Why not slide that scale to zero? Well, probably because there are benefits to stealth and VHF radar is not as easy or cheap as you believe it to be.

You can say that the F35 trades off too much and that a "less stealth" would be better. But that's fundamentally baseless speculation.

[sudosysgen]

Russian and Chinese stealth fighter-interceptors are fundamentally based on air defense and area denial missions. You're exactly right, their main use case is not to fly over enemy countries as much as flying over friendly countries, the ocean, and their own soil.

[hajile]

Stealth is necessary for attacking, but not defending. Further, stealth is only necessary for attacking sophisticated enemies.

Russia and China have no plans to attack the US within the next few decades, so they continue to research, but not to implement. It also doesn't help that US radar is a couple generations ahead as well.

Their current interests involve countries where a fast, hard-hitting plane is just as good as a stealth plane, so they save money at every stage from design to building to cost per hour flown.

[sudosysgen]

Stealth is just as useful for defending and for attacking, and arguably I'd say even more useful for defence because the attacker will never be able to field counter-stealth radars. Stealth when combined with counter-stealth radar on your home turf gives you a huge advantage as you now know a lot more about your enemy than your enemy knows about you. Non stealth aircraft plus counter stealth radar is a lot less of an advantage.

US VHF radar is likely not ahead at all. The US has never fielded a VHF radar, while the USSR and by extension Russia and China have done so since the 70s. The US has UHF radar and is definitely ahead in conventional radar though.

The interests of China and Russia do involve attacking sophisticated opponents such as Japan or Western Europe in order to destroy American infrastructure in a defensive war. It's just that instead of using stealth fighters to do so, they intend on using overwhelming numbers of missiles including hypersonic cruise missiles, of which the US doesn't even have a prototype yet.

These decisions weren't made in the last few years. They are tactical decisions as a matter of doctrine that were made in the late Soviet era. It's not a coincidence that these countries are ahead in counter stealth and ahead in hypersonics but behind in other things, they invested in what was most useful to fit their doctrine.