China built 10 missile cruisers in 48 months, packing 1,120 missiles

The parent's line of logic is sound; the United States has fundamental interests in securing Taiwan's independence. They are one of the very few countries that would receive Israel-levels of international intervention if their sovereignty was threatened, and China knows that. A ground invasion under current conditions would be political and materiel suicide; you have to imagine apocalypse-level global malcontent before NATO would roll over and go ahead with China's reunification strategy.

It didn't escalate quickly, you just didn't read the comment you replied to.

> I think in that case, the artillery shell production will be last of our concerns.

We're talking about the buildup of the chinese navy, not artillery shells. Though indeed, the presence of a massive nuclear arsenal renders the relative strength of conventional forces irrelevant for total war.

> China will progressively increase their exercises. First as like now to involve 50 airplanes and 20 ships...then 100 planes and 50 ships...then 250 planes and 100 ships, getting closer and closer to the last 20 to 25 miles of Taiwan, until the day the exercise will become an incursion, that goes for directly targeting heads of government. Probably by then hundreds of soldiers disguised as business men already will be in Taiwan.

I don't think you understand what is involved in launching a naval invasion. Taiwan has 23 million people, a standing army of 180,000 and 1.7 million reservists, and defensible terrain. A successful invasion without any US support would still be an undertaking an order of magnitude larger than D-day; its preparation would take months and be clearly visible to satellite imagery. Building the ships necessary to transport the troops would take years, and be at the expense of other naval production. Ships in transit and troops at mustering stations would be vulnerable to Taiwanese missile strikes. Whatever troops China managed to land would be severely outnumbered and outgunned by an entrenched opponent.

> Even if the US decides to intervene it will arrive days to weeks too late

The US would already be there. Again, they'ed have months if not years of advanced warning. There are already numerous American bases in the area, and America would likely pre-position forces on Taiwan itself if an attack was imminent. At the very least, it would lift restrictions on arms exports to Taiwan, allowing it to even better prepare its own defenses.

> You build a very strong army, either to defend or to attack. Nobody is a threat to China or want's anything from China, so they are not creating an army to defend assets...

China faced a century of humiliation because everyone wanted something from them and they had no means to defend their assets. They have long standing feuds with nearly every nation in the region. They are jockeying for position with the world's leading power. The claim they have no concerns about defense is absurd.