re: Could any strategy have worked in Vietnam?

Yes. Bomb North Viet Nam to a pulp. We almost won that war. But we snatched defeat from the jaws of victory. General Gap (head of North Viet Nam Army) admitted we almost forced them to surrender after a relentless bombing campaign by our Air Force. But our pal Walter Cronkite turned the tide in their favor. We wasted the lives of 60+ thousand men. A couple of those were my high school classmates. Many of those brave men who survived are now dying from exposure to agent orange. I know a few.