OK, that stops the book right there.
Didn’t they have satellites in this world?
You should read the synopsis in @dirtball’s link. It’s a hoot! The 20,000 Korean invaders arrive disguised as tourists.
Oh, well, then never mind. I’ve seen tourists. The amount of military-grade weapons they carry is frightening!
ETA. I took a quick look at the synopsis. That makes the tourist smuggling explanation seem like a work of Einstein’s comparatively.
There was a large genre of coming European war books before WWI. This resembles their idiocy, paranoia, bigotry, and sheer vacuity in all ways.
They got their weapons from local guerrilla groups. C’mon, read it! It’s the best laugh I’ve had all week.
Was this book adapted to movie form as Red Dawn? Wolverines!!!
Just the idea of Korea moving 20,000 people to the Mexican border undetected is laughable. Do they think Mexico or the cartels would allow that? How exactly would that size of a group manage to take over all those cities, with only small arms. No armor, no artillery, no air support. Do they know how many military assets the US has in those areas? Not to mention a US population that is at least as well armed as the invading force.
All of those questions are answered in the book (or, at least the synopsis of the book). Mexicans are united in their hatred of the Gringos and welcome their Korean liberators. All US military is currently engaged in Asia. Much of the US population is made up of Hispanic and Asian immigrants who all hate their white American oppressors. The answers are all ridiculous but all of the questions you and others have asked in the thread are addressed.
Sorry, I just say no to reading web pages with dark background and white print. Now that you’ve explained it to me, who am I to get in the way of such a sound plan? 
(does not run out to purchase the book)
Don’t forget, it’s entirely the 20,000 Koreans vs only the Texas National Guard because apparently if other National Guard units are sent into Texas to help that will “Tank the Stock Market” so Texas is all alone.
Yeah, and the rest of the US don’t really care since they all hate Texas, anyway…well, it’s not all far fetched.
Is hoarding a fast zombie trait, or a slow zombie trait?