Earlier quoted context omitted.
Does Taiwan count as part of China? A brief look at the Taiwan-China relationship shows it's a more difficult question than it initially seems
According to China (the People's Republic of China), Taiwan (the Republic Of China) is a "renegade province." Both the PRC and the ROC claim that they are the legitimate government of China. In the US, ever since Nixon instituted the "two China" policy, China is always taken to mean the PRC. Perhaps the security researchers are not aware of this distinction, but I am also not familiar with how the issue is treated in…
Taiwan is not a "major" US ally, rather the US is Taiwan's major ally. The US has several other regional countries it has a significantly greater alliances with, such as Japan, South Korea and Philippines. Though through an act of Congress, the US may (depending on the situation) have some obligations to aid Taiwan in its defense if attacked by mainland China.