That's the second Indochina war, and American bombing was mostly done against Vietnamese targets in the jungle in the neighboring countries, so mostly it was still Vietnam. But yes, they regularly hit civilian targets in the neighboring countries.

The first Indochina war was France testing its contemporary new and shiny western military doctrines in the wild and finding them lacking.

In general this seems to be a pattern, western nations indeed value lives of their soldiers very much. I doubt it's because of humanism (they don't value enemy civilian population's), rather because of inherent racism. But it shows in the doctrines, they are always looking for a way to create a situation where they can hit their enemy, but their enemy can't hit them, and where they are moving so much faster than their enemy, that their enemy could as well be a sitting duck. To create a baby beating disposition. That's harmful for military's experience and esprit de corps, but appeals to the western nations' feel of superiority. Long term harm, short term impressions.

So - it didn't work. They were using air logistics and supply depots in a system all over the place and small expert mobile forces and all that stuff the western public still considers proper way of fighting a war. In other words, they tried to cheat. And Viet Minh just did their work honestly, in many small steps, over long enough time.

Of course the French logistics were conditioned by fighting on the other side of the globe from metropoly, and Viet Minh fought at home. But honestly it seems to be a pattern in all wars for any European nation, ideas of superiority and quick spectacular solution are always replaced for more classical understanding once actually tried. It's a cliche that USSR's approach was mass assault with no regard for lives, but, ahem, Tukhachevsky is one of the creators of the ideas that became Wehrmacht's doctrine in the beginning.

While the USA in Vietnam decided to show another thing - that they are not France and can just burn all of the fucking jungle with their power. And they burned much of that, except their population wasn't ready even for the pretty moderate losses there (like 4x what USSR lost in Afghanistan).