So far, though the attempted Mongol invasions of Japan, while premodern, were on a similar level of difficulty. The sea between Taiwan and mainland China is re

So far, though the attempted Mongol invasions of Japan, while premodern, were on a similar level of difficulty. The sea between Taiwan and mainland China is really a formidable obstacle to such operations, even without radar, advanced missiles and drones. Ships are expensive, slow and vulnerable; even the Russians had to yield in the Black Sea after suffering serious losses against a nation with no navy.