Semi is the most globalised industry spanning 28 countries, with USA, China, Taiwan, Thailand, Malaysia, SK, Japan, Germany, Belgium, Netherlands being able to singlehandedly stop the whole of it.
It's a naive thinking "once TSMC will complete Arizona megafab, we can abandon Taiwan." There, are as I said, hundreds of critical single supplier globally pieces of equipment, services, and materials that most of the world had zero idea about. How about nanoneedle probes capable of testing M0 the entire industry depends on, for which there is 1 small company for the entire world.
The DoD has identified the loss of manufacturing capability as a national security risk. Maybe lower labor costs were the impetus of off-shoring manufacturing, but nearly 40 years since globalization took hold there's also a lot of manufacturing that has to go overseas simply because America is no longer able or willing to do it. Could the US bring back that capability? As you said, even if there was the will it wouldn't happen overnight.
US semiconductor equipment from LAM, and Applied Materials are more than half imported parts. US semi industry never used OSATs, until it had to ship their chips to Asia for that, and thus missed out on most of new packaging, and test tech which evolved outside of the US. Similarly for almost everything else.
Replacing Asian material suppliers for the US will be as hard as for China to develop a domestic photolithography stepper.
Ok, then we'll stop talking.
"We will betray our allies, and they will leave us alone" is a form of defeatism, and entertaining others into this way of thinking is not what a citizen of NATO country should do, let alone a public figure.
This is true. And it is the main driver behind the United States' renewed interest in domestic fab capability:
https://www.congress.gov/bill/116th-congress/house-bill/7178
Taiwan isn't explicitly mentioned but it plays a large role in the reasoning behind this.