LBJ escalated the war in Vietnam because he didn't want to be the first President to lose a foreign war. He also believed his generals who told him just a more divisions will "finish the job".
Perhaps the most fatal error he and his entire administration made was they believed the South Vietnamese people they went all the way at great US sacrifice to "save" shared their values on just about everything -- on Vietcong, Ho Chi Minh and on democracy.
Brezhnev was "invited" by the Kabul government to fight against the Islamic Mujahideen. That war lasted 9 years with 100,000 Soviet troops on the ground.
A US military study later claimed the Soviets did not have enough "boots" on the ground. Right now, with the expected troop increase of 30,000 +/- Obama will announce tomorrow, US and allies will have more than 100,000 troops with most of them GIs.
You can count on the military to argue that 100,000 ain't enough given what both that study says and what General McChrystal has said openly. You can also count on whom the military will blame should they fail to "finish the job".
Incredible as this may seem, since so many analysts have drawn the comparison of this war to the US misadventure in Vietnam and the Soviet one in Afghanistan, Obama and his advisors are repeating the same fatal conceit.
They really don't appreciate the deep historical significance of Afghanistan as the place "empires go to die". Clearly the current leaders continue to believe in itself as being fundamentally different from all previous foreign empires since time immemorial. America is the Exception is as American as apple pie, as it were.
Here are just a couple of relevant passages from the Wall Street Journal report:
..."Few American officials know the Soviets' bitter Afghan predicament better than Mr. Gates. In the 1980s, he was the deputy director of the CIA, overseeing a massive U.S. effort to fund, train and equip the Islamic insurgents, called mujahedeen, who fought the Soviet army to a standstill.
Now some of the most prominent of these insurgents, such as Gulbuddin Hekmatyar and Jalaluddin Haqqani, are allied against America with the Taliban and al Qaeda. Almost daily their men are killing Western troops, who often operate from former Soviet bases and use Soviet-drawn military maps with faint Cyrillic markings.
"It's an eerie sense of deja vu," said Bruce Riedel, a Brookings Institution scholar who headed the Obama administration's Afghan policy review in the spring and who in the 1980s worked under Mr. Gates as a CIA officer in the region. "America," he said, "is in the rare position of fighting the same war twice in one generation, from opposite sides. And it's easier to be the insurgents"...
...Despite billions in U.S. aid since 2001 spent on roads, clinics and schools, there is little comparably prominent evidence of American reconstruction.
"What have the Americans done so far? They're only busy building their own military bases," said Mohammad Nassim, a 40-year-old Kabul resident, airing a frequently heard opinion....
...Portraying Americans here as the new Soviets, of course, forms the very foundation of the Taliban world view. "Both superpowers wanted to impose by force their alien ideologies on our country -- the Soviets socialism, and the Americans this strange phenomenon they call liberal democracy," Mullah Wakil Muttawakil, foreign minister of the Taliban government that was deposed in 2001, said in an interview. "These are outside ideas. And anything coming from abroad is resented and rejected here."...
The full WSJ report is here.