From Taipei Time:
For more than 50 years, the US has enjoyed a remarkably close relationship with Taiwan. Arguably, no other country maintains as many ties with Taiwan. What lies behind US interest and how has it changed over time?
During the late 1940s, US military planners described Taiwan as an "unsinkable aircraft carrier" and warned that, while it might not improve US military capabilities in East Asia, the island would certainly enhance the military capabilities of any power hostile to the US.
Even today, some fear that if Beijing takes over Taiwan, it would "unleash" China, which might project its military influence outward over the Western Pacific. [Full Text]