Maybe US just finally met nation/group of individuals pissed off enough to care and go and deliver revenge the deem adequate. I mean, expecting that some random casualties ratio being upheld means all is a-OK is a bit ridiculous, don't you think?

After all the hell and atrocities done by US in Vietnam, I absolutely do not understand how there was no strong resent towards US anymore after the war to the point of actively seeking and eliminating US targets like terrorist/spies do.

It was a humbling realization for me, and I have great respect for Vietnamese people not only for this.