The stealth bombers are a big advantage for the US because no one has an equivalent, and China’s equivalent is probably a decade away. The B-21 is based on the same concept as the B-2, but smaller so that more can be produced, the US Air Force wants over 100 of them, with some officials wanting 200. It also features upgraded stealth, known as “broadband stealth” to be stealthy from all angles, against radars of varying frequencies, and a further reduction in infrared signature. Lots of work has been done on the engine inlets and exhausts to reduce the radar and infrared signature when viewed from above and behind compared to the B-2. It’s why the inlets look so weird, and there are no clear photos of the exhaust. The “zigzag” rear edge on the B-2 which was implemented to improve low altitude performance has also been removed. Bombers can deliver a payload that fighters simply cannot, as shown by the Iran strikes. This is their huge advantage.

The challenge with stopping a B-2 or B-21 is not shooting down a single bomber. The bomber just delivers the massive payload, such as two 30 000lb bunker busting bombs, 16 tactical nuclear bombs, or 80 500lb conventional bombs. They don’t go in alone. The challenge is stopping the entire strike package. In Iran the US sent in over 100 aircraft. F-22s sweeping the airspace to take out any aerial threats and providing escort. F-35s with anti radiation missiles and air to air missiles suppressing air defences and escorting the stealth bombers. EA-18Gs doing wide spectrum jamming and suppressing air defences with anti radiation missiles. F-18s with air launched SM-6 missiles that can hit aerial targets from hundreds of miles away. Even some F-16s. That sort of thing. This is almost impossible to stop for most nations.

The method described here to take out a stealth bomber could work, in isolation. A (likely stealthy) Chinese drone passively detects the B-21 while working with a Chinese stealth aircraft, and calls in a long range missile from said aircraft to try take out the bomber. But in reality, that requires the Chinese drone and aircraft team to detect and get a firing solution on the bomber before the US strike package detects and destroys them. Which is very, very challenging.

The airspace over mainland china wont even be meaningfuly contested by the US even in the case of a us-china war in the theater. Iran had like single digit numbers of outdated for Chinese standards AD batteries, no airforce, no ground base radars, no awacs. B21 are formitable but it the iran engagements says nothing regarding how they would fare against actual technological peers employing platforms at equal or greater numbers.

No b21 bombing campaigns over mainland China arent surviveable. Especially given thatby the time the US will have enough of them to accept idk 30%+ losses for some valuable target, China would be rolling out their six gens , will have widened the gap in radar tech, they will have 1k 5th gens, they will have prob the largest and most capable awac fleet and the air defense network around most valuable targets will be suffocating.

My take from the Iran bombing was that these stealth bombers are the most dangerous single weapon the US has because nobody has any capacity to defend against them.

If an American bomber drops a load on one of your cities or important targets and your not sending a nuclear missile to Washington in response then you’ve already lost the plot. China has absolutely nothing to worry, its the other countries without capability to retaliate that do. But in their case who cares about stealth bombers when the full combined force of US plus allies is enough to overwhelm your military in the first place?

Countries that can defend themselves like all the ones with nukes vs countries that will get bombed regardless if its a stealth bomber or not.

Stealth is a win more technology. Imagine NATO uses a stealth bomber to attack Russia, what could they realisticaly hit that wouldn’t invite massive retaliation? Russian non-nuclear assets? Russia doesn’t have stealth bombers, yet they must respond somehow and the US knows it. In that scenario using the stealth bombers, inciting a response the Russians can’t match except through escalating towards nuclear response is no different than launching your own nukes in the first place.

Escalation theory relies on you understanding and respecting your enemies capabilities too, leaving them with no viable response but to escalate is madness. So in reality there are no countries you could use this against except the ones the US already dominates against militarily. All other possible peers(China, India, Russia) in the world also have nukes and other technologies of their own.

So we have the Iranian example, a country where the US would defeat easily in an air campaign regardless given the incredible air power difference. Yet even then the B-2s did not go in at the very beginning but the opposite, at the very end after Iranian AD was already severely limited.

Its why stealth is barely above military porn, its a win more tech, perfectly aligned with the US doctrine of imposing fear of an irresistible air campaign aka the 20th century US air doctrine, which is only really a threat to countries without the capability to retaliate.