A non-nuclear weapon design involves what are called kinetic energy impacters. These are tungsten rods that travel in earth orbit. They can be deorbited to hit a spot on the ground. The rods use their orbital speed, which can be more than eight kilometers per second, to provide the kinetic energy to penetrate and destroy targets.
The main purpose of such proposed weapons is to destroy deeply buried bunkers or caves and kill the people in them. As far as I can see, such weapons can also destroy dams.
This kind of weapon might be a non-nuclear, but effective deterrent for Taiwan against mainland China. In particular, with such a weapon, Taiwan could threaten to destroy the Three Gorges Dam on the Yangtze River.
Obviously, the dam is well protected against airplane and cruise missile attack. However, at the moment, the military in mainland China do not have a non-nuclear capability to defend against kinetic energy impacters. They would have to emulate the US and explode nuclear bombs to destroy satellites carrying the rods or to destroy descending rods. They might not be keen on detonated such bombs over their own territory.
And, of course, they might not be able to destroy or deflect all the tungsten rods of an attack; a defense might not work.
Those parts of Taiwan that wish to remain independent of mainland China have the motivation to develop some kind of deterrent against mainland China and this is one possibility.
Clearly, mainland China thinks as much in political and business terms as in military terms. At the moment, Taiwanese businessmen are investing huge amounts in mainland China and this gives influence to the mainland China government.
But military force also provides influence. Since the US government is shifting away from Taiwan towards mainland China both to fund its current deficit and for trade, it behooves Taiwan to consider what it can do itself.
Ordinary liquid rockets can loft kinetic energy impacters into orbit. That is expensive and hard. It will also be expensive and hard to develop air augmented rocket engines, but their incremental cost should be less.
In my page on Inexpensive Earth to Orbit Rockets, I talk about the use of air augmented rocket engines. In such a design, oxygen is taken from the air for part of the flight. Because the rocket does not have to carry all its own oxidizer, its effective specific impulse doubles. This lowers the incremental cost.
Finally, solid rockets, like those used as boosters for the US Space Shuttle can be developed. These engines are expensive and hard to develop, too. And their incremental cost continues high, just like regular liquid fueled rockets.
Their first advantage is they store well and can be launched quickly. This is why the US and USSR developed them for ballistic missiles.
A second advantage is that solid rockets can be built large and can therefore carry heavy loads into orbit. I think that once regular sized solid rockets are developed, it is as easy or easier to increase the size than to increase the size of regular liquid fuel rockets. I could be wrong on this, but I seem to remember this from public discussions about large solid rocket engines in the 1960s.
It is not easy to develop solid rocket engines. The Soviet Union took a generation or more longer than the US. But it can be done.
As I said, solids cost more per launch than air augmented rockets. That is one reason that space shuttle launches are so expensive. This is a disadvantage. A second disadvantage is that solids put aluminum oxide from the fuel exhaust into the upper atmosphere. This is more harmful than water.
However, from a combination of military and accounting points of view, large solids may be attractive.
I do not know if Taiwan is doing anything like this: I am simply considering countries that have the motivation and the capabilities, financial and technical. Taiwan is, I think, one of them.
The only country known to be working on kinetic energy impacters is the United States. I do not think its program is very large or advanced, but could be wrong. (If the US already had accurate kinetic energy impacters, I would expect the US to use them to destroy caves in Afghanistan.)
Does any know more?