Until the administration of US President Donald Trump, Washington had always been of two minds regarding Taiwan’s importance to US national interest.
In the post-World War II period, when Taiwan was controlled by Chiang Kai-shek (蔣介石), a US ally, but a harsh dictator, then-US president Harry Truman’s administration saw no need to get in a war with China over the nation.
In 1949 and 1950, speeches by US General Douglas MacArthur and then-US secretary of state Dean Acheson excluded Taiwan (and South Korea) from the US Pacific defense perimeter, and the US Navy was removed from the Taiwan Strait and nearby waters.