As a former Air Force Systems Analyst Officer (1972-1976), the part of Vietnam that I remember is that in 11 days of unrestricted bombing and air dropped mines, Operation Linebacker II put all of North Vietnam's ports out of business. This cut off all supplies, because the Red Chinese skimmed 90% plus of what was shipped overland. If Linebacker II had been launched in 1965 instead of December, 1972, it would have saved a lot of lives and made Counter Insurgency (COIN) a lot more effective, a lot earlier. We lost in Vietnam because between 1973 and 1975 Congress cut aid to South Vietnam by 75% and outlawed US air strikes anywhere in Southeast Asia. Congress and the American people lost patience with the Vietnam War. If we had bombed in 1965 and kept bombing, we would not have had Congress outlaw air strikes after we had won in 1967 or 1968.
The part of strategy in guerrilla war that the US has forgotten is that without supplies, guerrillas die. Guerrillas don't have the luxury of growing food or manufacturing ammunition for themselves. They're on the run. Rangers in the American Colonies originally got their name because they ranged through Indian territory and attacked Indian farming villages, which were the base of Indian supplies. The US beat the Plains Indians by almost exterminating the American buffalo, which the Plains Indians used for food, clothing and shelter. Hunting the American buffalo to extinction was an intentional strategy originally proposed by General William T. Sherman. It was carried out ruthlessly, and it worked exactly as planned. The Plains Indians moved onto reservations because they had nothing to eat.
Recently, we have watched ISIS go from strong to dead because we eliminated their source of income, oil sales, by bombing their tanker trucks, oil fields and oil handling facilities. I don't mean to make light of the combat efforts it took to eliminate ISIS, but I do want to point out that ISIS was far less formidable broke than they were when they were rich. Eliminating their financial resources made them far easier to defeat.
Which brings us to Afghanistan. The Taliban runs on opium sales. Everybody knows it. To eliminate the Taliban, we need to eliminate their opium sales. We can either legalize opium world wide, which would lower the value of the opium sold, or we can destroy all Taliban opium exports coming out of Afghanistan. Since legalizing opium is highly unlikely, the only alternative is destroying all opium exports. Anything less and we still have a rich Taliban who can hire soldiers and pay for food, guns and ammo. We haven't done this because Afghanistan's main foreign exchange earning export is illegal opium sales. However, unless we do something about Taliban opium, the best outcome we can hope for in Afghanistan is a steady state of what the Israelis call "mowing the lawn." We can use air power and special forces to limit the Taliban to controlling 40% of Afghanistan. We can't win in Afghanistan unless the Taliban can't sell their opium to finance operations.
To defeat the Taliban, we would have to eradicate opium systematically, using air power, in all areas the Taliban controls or even partially controls. If the Taliban controls your poppy field, the US will destroy your crop. If you want to keep your crop, keep the Taliban out of your area. Otherwise, the US puts napalm on your poppies. Displaced farmers will move to areas under government control. There will be no people, and no money, for the Taliban to use to support their operations. At that point, COIN (COunter INsurgency operations) will work a whole lot better.