"Need" defending? I couldn't care less who rules Ukraine, Taiwan, Syria, Libya, Afghanistan, Iran, and these countless other places half-way around the world. It's not like China taking over Taiwan will have any impact on semiconductors. They're happy to play merchant to the world, independent of allegiance. E.g. - Ukraine complains about China supplying Russia with tech for their drones, while failing to recognize the countless "Made in China" stamps on their own hardware.
When despots act subservient to the US we're more than fine being BFF with them. See: Saudi Arabia. Heck we're even aiding them in their little 'special military operation' in Yemen. So funny how the rhetoric changes depending on who's involved: "On 26 March 2015, Saudi Arabia, leading a coalition of nine countries from West Asia and North Africa, staged a military intervention in Yemen at the request of Yemeni president Abdrabbuh Mansur Hadi, who had been ousted from the capital, Sanaa, in September 2014 by Houthi insurgents during the Yemeni civil war." [1]
So a president is overthrown by a popular insurrection, and then another country which was fond of the old government decides to take advantage of the situation to invade, primarily to further their own ends. This sounds oddly familiar, yet somehow the rhetoric around it is entirely different. Nah, I'm tired of this nonsense. If a country literally invades another country which we have a military alliance with then yeah - we have an obligation to intervene. But without that - I can think of far better ways to spend trillions of dollars than killing people half-way around the world.
[1] - https://en.wikipedia.org/wiki/Saudi-led_intervention_in_the_...
> I couldn't care less who rules Ukraine, Taiwan, Syria, Libya, Afghanistan, Iran
Oh you will. You most certainly will.
No I won't. No I certainly won't. This nonsense is fun for shit posting on the internet but it literally does not matter. Countries are driven by self interest. If we wanted to stop dicking around in other country's affairs then we could be trade buddies with pretty much whoever we wanted with absolutely zero consequence to ourselves, and likely substantial benefit.
The thing about nukes, to say nothing of US geography, is that the chances of us being attacked is literally zero, unless it's a doomsday type nuclear bombardment affair. We don't even have to worry about things like a decapitation attempt since we're not surrounded by hostile military bases, or any other country's military bases for that matter.
Whatever the rest of the world wants to do - that's their problem. This isn't necessarily isolationist because I'm perfectly happy trading and engaging in any positive way with other nations, but this sort of 'nation building' and geopolitical crap we try to do just about always fails, and the few times it hasn't (like South Korea) is far more incidental than consequential. We left them with an endless series of awful dictators in charge and they somehow stumbled their way into becoming a half decent place, independent of us.