Why would the US be concerned about the meaning of Asia for Asians?

Answer 1

"Asia for Asians" was a slogan used in Propaganda campaigns across Asia by the Japanese Empire immediately prior to, and throughout, the Second World War.

It was intended to promote anti-Western feelings in Asian countries. As most Asian countries had (at that time) European or American imperial overlords, the slogan was created to encourage native Asian populances to side with the Japanese.

It was particularly cynical, since the idea was to encourage the native population to resist European/American rule, but the actual Japanese policies were not to help Asian counties become independent, but to instead conquer those countries for Japan. Thus, while the slogan may appear to promote national self-determination (a good thing), the policies behind it were merely to replace European or American Imperialism with Japanese imperialism.

In current times, the slogan is sometimes used by xenophobic ultra-nationalists in a variety of different countries. Xenophobia is a very bad thing in the modern, highly interconnected world, with ultra-nationalism even worse.