[Goose]

The US realized that letting Russia break the rule-based system of international relations would be a very serious blow to the world and to the US in particular. Unfortunately it appears that we have, yet again, abjectly failed to accomplish our mission.

Agreed.  

Ukraine's fall, should it happen, dramatically increases the odds that China will invade and conquer Taiwan.

Totally agree. There is also a significant pro-Bejing political element in Taiwan. They will be strengthened by the fear Taiwan will be on their own and has to make the best deal possible.

It also increases the probability that Taiwan decides to   Taiwan knows this.  If I were Taiwan I would be accelerating a nuclear weapons program.  In fact, my guess is that many countries are doing just that, given how unreliable an ally America has become.

For Taiwan, this is a tough one. When the word gets out this is happening (and it will. The place leaks like a sieve), China has a ready-made excuse to invade Taiwan before they succeed. It may ensure an invasion that otherwise may never come. OTOH, if they don't they may be unable to resist such an invasion.

Imagine what position Ukraine would be in if they had not given up their nuclear weapons.

They would be in a disastrously BAD position. They would have a bunch of H-bombs that are 20 years past the absolute maximum rebuild date with unstable precursors that could spontaneously explode any minute. USSR warheads were not designed for a long shelf life. They require periodic re-manufacturing (about every 10 years, 15 years absolute max) and without it they are dangerous. If you launch one of those weapons (on a missile that is equally old and probably liquid fueled) it is not at all improbable the warheads explodes from the shock of launch. It may not be a thermonuclear detonation (although it might be) but it would at a minimum be a dirty bomb detonated in Ukrainian territory. If it doesn't do that and reaches the target inside Russia (by no means certain given the age and technology of the delivery vehicle), it may or may not "work". In either case Ukraine could expect a massive Russian nuclear response.

Ukraine had no capability to rebuild the warheads. That was all inside the Russian Federation. Obviously they would have received no help in creating such a capability. Ukraine knew all this when they "gave up" the warheads and the launch platforms. They would have driven a much harder bargain if they had weapons that would actually be useful in 10 years.

For that matter, there has been some journalism suggesting that Ukraine could develop rudimentary nuclear capability within months.  They do have seven tons of plutonium.
https://www.thetimes.com/world/russia-uk...-0ddjrs5hw
Given recent developments, why not?  I almost think that Zelensky would be derelict in duty if he were not attempting to get his hands on a nuclear weapon.

A "dirty bomb" would not be all that useful to Ukraine. It might make a few square miles of Russia temporarily (or longer) uninhabitable. That isn't enough damage to be any kind of a "knockout" blow. It wouldn't actually move the meter much. It would however give Russia an iron-clad justification to use tactical nuclear weapons in Ukraine. "They nuked us, we nuke them, only more and better".  A single nuclear weapon (obtained however) could do a lot more damage. Using it would not end the war however, and would unleash a (very) small subset of the Russian strategic deterrent on Ukraine. That would end the war, and Ukraine too.

I am not an international relations expert, but it seems to me that the risk of the proliferation and use of nuclear weapons has dramatically increased over the last few weeks.

I agree that it has. Some non-nuclear NATO countries plus Japan will certainly think about it. They have the money and technology to do it reasonably rapidly. The problem with using nuclear weapons as a deterrent  against the US China, or Russia is that the "mutual assured destruction" (MAD) has to be mutual in order to work. Yes, North Korea could possibly strike the US with a few warheads. That would be horrible. The US would obliterate North Korea. The US would continue to exist. North Korea would not.

The relatively smaller number of nuclear weapons most "small" states can produce aren't all that destabilizing in themselves. The problem is that the leaders of these states may misinterpret the strength it gives them and overreach. An example of this is India and Pakistan. Do they have a MAD relationship that precludes either side using nuclear weapons? Unclear. China-India is even more problematic. India's 172 (or so) warheads are less than half of China's 500 (or so). If China and India clash in a conventional war in the North, at what point does India decide it has to use nuclear weapons to avoid defeat? Perhaps they feel a first strike is their only hope because their second-strike capability would be inadequate?

For a long time the Cold War kept everybody "on side". That is no longer the case. As long as the US (NATO) and the Russian Federation didn't start  conventional wars oriented toward changing the balance of forces everything continued along pretty much as before. Russia has now crossed that line. The reality is that Ukraine having a few nuclear weapons does them no good because they probably could not deliver enough damage to deter Putin. The question would become "How strong a nuclear force is required to deter Russia?" and "How do we know when we have that force?". Indeed a very fraught situation.

[Goose]

The US realized that letting Russia break the rule-based system of international relations would be a very serious blow to the world and to the US in particular. Unfortunately it appears that we have, yet again, abjectly failed to accomplish our mission.

Agreed.  

Ukraine's fall, should it happen, dramatically increases the odds that China will invade and conquer Taiwan.

Totally agree. There is also a significant pro-Bejing political element in Taiwan. They will be strengthened by the fear Taiwan will be on their own and has to make the best deal possible.

It also increases the probability that Taiwan decides to   Taiwan knows this.  If I were Taiwan I would be accelerating a nuclear weapons program.  In fact, my guess is that many countries are doing just that, given how unreliable an ally America has become.

For Taiwan, this is a tough one. When the word gets out this is happening (and it will. The place leaks like a sieve), China has a ready-made excuse to invade Taiwan before they succeed. It may ensure an invasion that otherwise may never come. OTOH, if they don't they may be unable to resist such an invasion.

Imagine what position Ukraine would be in if they had not given up their nuclear weapons.

They would be in a disastrously BAD position. They would have a bunch of H-bombs that are 20 years past the absolute maximum rebuild date with unstable precursors that could spontaneously explode any minute. USSR warheads were not designed for a long shelf life. They require periodic re-manufacturing (about every 10 years, 15 years absolute max) and without it they are dangerous. If you launch one of those weapons (on a missile that is equally old and probably liquid fueled) it is not at all improbable the warheads explodes from the shock of launch. It may not be a thermonuclear detonation (although it might be) but it would at a minimum be a dirty bomb detonated in Ukrainian territory. If it doesn't do that and reaches the target inside Russia (by no means certain given the age and technology of the delivery vehicle), it may or may not "work". In either case Ukraine could expect a massive Russian nuclear response.

Ukraine had no capability to rebuild the warheads. That was all inside the Russian Federation. Obviously they would have received no help in creating such a capability. Ukraine knew all this when they "gave up" the warheads and the launch platforms. They would have driven a much harder bargain if they had weapons that would actually be useful in 10 years.

For that matter, there has been some journalism suggesting that Ukraine could develop rudimentary nuclear capability within months.  They do have seven tons of plutonium.
https://www.thetimes.com/world/russia-uk...-0ddjrs5hw
Given recent developments, why not?  I almost think that Zelensky would be derelict in duty if he were not attempting to get his hands on a nuclear weapon.

A "dirty bomb" would not be all that useful to Ukraine. It might make a few square miles of Russia temporarily (or longer) uninhabitable. That isn't enough damage to be any kind of a "knockout" blow. It wouldn't actually move the meter much. It would however give Russia an iron-clad justification to use tactical nuclear weapons in Ukraine. "They nuked us, we nuke them, only more and better".  A single nuclear weapon (obtained however) could do a lot more damage. Using it would not end the war however, and would unleash a (very) small subset of the Russian strategic deterrent on Ukraine. That would end the war, and Ukraine too.

I am not an international relations expert, but it seems to me that the risk of the proliferation and use of nuclear weapons has dramatically increased over the last few weeks.

I agree that it has. Some non-nuclear NATO countries plus Japan will certainly think about it. They have the money and technology to do it reasonably rapidly. The problem with using nuclear weapons as a deterrent  against the US China, or Russia is that the "mutual assured destruction" (MAD) has to be mutual in order to work. Yes, North Korea could possibly strike the US with a few warheads. That would be horrible. The US would obliterate North Korea. The US would continue to exist. North Korea would not.

The relatively smaller number of nuclear weapons most "small" states can produce aren't all that destabilizing in themselves. The problem is that the leaders of these states may misinterpret the strength it gives them and overreach. An example of this is India and Pakistan. Do they have a MAD relationship that precludes either side using nuclear weapons? Unclear. China-India is even more problematic. India's 172 (or so) warheads are less than half of China's 500 (or so). If China and India clash in a conventional war in the North, at what point does India decide it has to use nuclear weapons to avoid defeat? Perhaps they feel a first strike is their only hope because their second-strike capability would be inadequate?

For a long time the Cold War kept everybody "on side". That is no longer the case. As long as the US (NATO) and the Russian Federation didn't start  conventional wars oriented toward changing the balance of forces everything continued along pretty much as before. Russia has now crossed that line. The reality is that Ukraine having a few nuclear weapons does them no good because they probably could not deliver enough damage to deter Putin. The question would become "How strong a nuclear force is required to deter Russia?" and "How do we know when we have that force?". Indeed a very fraught situation.