I do not think you can compare this conflict with Vietnam. US army went into Vietnam, while Ukraine is fighting a US rival with their own military, but they do use US provided equipment.
General public in Europe didn't see US as actively involved, or at least didn't see it until the new administration said it would end the conflict. This is when Trump administration started getting into "talks with Russia" and offering Ukraine "mineral deals". While US might have tried to do that even before, it was not discussed openly by presidents.
This war is going to flame out eventually. Lessons learned in this one will be used for the next one, which is going to hurt even more.
General public in Europe didn't see US as actively involved, or at least didn't see it until the new administration said it would end the conflict. This is when Trump administration started getting into "talks with Russia" and offering Ukraine "mineral deals". While US might have tried to do that even before, it was not discussed openly by presidents.
This war is going to flame out eventually. Lessons learned in this one will be used for the next one, which is going to hurt even more.