“Are they pin-pricking, taunting the giant?”
Exactly. China called our bluff to see how we would react, in fact how SE Asia would react. That is why Korea and Japan are involved.
China found out where these countries stand. China isn’t ready to challenge the Pacific powers yet.
I think SE Asia refers to anything south of China.
Don't be too sure of that. When Lt. Commander Edwin Layton was sent over by Admiral Kimmel's headquarters (where he was Kimmel's intelligence officer) to visit Admiral Pye, commander of the Battle Force (BB's), aboard USS California, on the eve of the Pearl Harbor raid, Pye's take on the Japanese evolutions toward Malaya and the intelligence on the "missing carriers" (the Kido Butai that sank Pye's flagship about 16 hours later) was something like, "Oh, they wouldn't dare attack us -- we're too big and strong." It was an opinion shared by many.