The US didn't win the Vietnam War and didn't even unambiguously win the Korean War.

What the US did was show it would make life uncomfortable for those who challenged the liberal trade order and politically-and-economically offer benefits for those who embraced this order.

What Trump has done is just attack Iran (during negotiations) with no real counter-offer. Iran has responded by attacking everything in sight because nothing was being offered by the US.

Clearly the result is indeed a serious failure on the part of the Trump administration but it's a failure that seems to come from not even understanding that "Pax Americana" has depended on the carrot and the stick.