Hey guys I've been doing a bit of reading on the "10 Year War", but I'm kind of struggling to understand why the Soviet Union even wanted to invade in the first place, I'm also kind of stuck on understanding the aftermath of the entire thing. Hopefully you guys could throw some bullet points my way, or anything for that matter! Thanks
why the Soviet Union even wanted to invade in the first place
Here's events and causes which trigger intervention:
"Saur revolution" of 1978 was accidental coup d'etate. It started after Daoud (who himself overthrew his cousin, King Zahir, in 1973) has ordered crack down on leftist parties. During crack down, Mir Akbar Khyber - a prominent leader of PDPA (Parcham faction) was killed (exact circumstances are still not clear). Although Daoud's government officially deplored the assassination, it was widely blamed on Daoud security service. PDPA (Halq faction) was strong in army and especially in Air Force and they were scared into action. Amazingly, even weak and spontaneous action was enough to topple Daoud - illustrates perfectly the chronic weakness of the central government. Problem was, after they took power, they do not know what to do with it - they were officers, not politicians. Add to that PDPA schism into two warring faction, loss of its leader and lack of popular support - most peasants never even heard about PDPA.
Pro-USSR attitude was prevalent among afghan officers - a lot of them were educated in USSR (esp. Air Force). Many supported communist ideology and wanted same level of life as in USSR. They didn't like Daoud's coup and his eventual turn to West.
Afghanistan leadership (first, Nur Mohammed Taraki and then Hafizullah Amin) have asked for assistance from USSR military troops quite often. Those requests were routinely denied, per advice from USSR military leadership (GenShtab, Minister of Defense) - which never liked the idea of going into Afghanistan.
Nur Mohammed Taraki was killed by Hafizullah Amin during power struggle. Taraki has tried unsuccessfully to remove Amin - who sidelined Taraki by mid-1979.
Amin always was a hardliner. He repressed all potential rivals in PDPA, not only in Parcham faction, but in his own (Halq) too. Including officer corp. This alienated many people from the PDPA regime. His aggressive stance against any opposition and lack of popular support were most serious arguments for his removal. And his removal was direct cause for intervention.
By December of 1979, USSR leadership felt that the only option to reign in Amin is to overthrow him. Taraki's murder really incensed Brezhnev and motivated him to push thru with Amin's removal, despite objections from GenShtab. As Amin's opposition in PDPA proved to be hapless (plus, two USSR attempts on Amin's life failed and Amin got very cautious), invasion became the only viable option. Note that both Amin and Taraki were from Halq faction.
PDPA policies and Amin's touch on them has led to insurgency. Most notable was uprising in Herat.
KGB liked Parcham faction more than Halq. KGB leadership was at odds with top military brass, actively advocating for invasion. Later (by 1983) Andropov has reversed position and he actually initiated Geneva talks in 1982-83.
I've posted more on Amin vs Taraki affair in this thread (with sources): http://www.reddit.com/r/AskHistorians/comments/1whvm3/how_did_hafizullah_amins_behaviour_influence_the/
I will address aftermaths in separate wall of text.
Sources
Afghanistan: Lessons from the last war. Volume II. The soviet experience in Afghanistan: russian documents and memoirs, 2001, ed. by Svetlana Savranskaya. A lot of primary sources, with commentaries in English. This is what you want to study and analyze if you want to understand why the decision was made.
Rodric Braithwaite - The Russians in Afghanistan: part I. This is excerpt from the book "Afgantsy: The Russians in Afghanistan 1979-89" by Rodric Braithwaite (who was a British diplomat, posted in Moscow in 80s). You could find the book on Amazon. While it is mostly focused on military operations and personal accounts of russian veterans, it provides high-level overview of causes and consequences.
Peter Tomsen - The Wars of Afghanistan: Messianic Terrorism, Tribal Conflicts, and the Failures of Great Powers (Google eBook), 2013. I haven't read it yet, but it cites a lot of verified sources and looks well-written at a glance.
Gilles Dorronsoro - Afghanistan, Revolution Unending: 1979 to Present. I've linked review of this book, you could find it on Amazon. While in general a good top-level overview, it is very biased toward Akhmad Shah Massoud - it completely ignores the fact that Massoud has several high-level agreements with 40^th Army leadership and does not analyze differences between OKSVA policies and DRA policies.
(Russian, online book) A. A. Lyakhovsky - The tragedy and valor [of the veterans] of Afghan[istan] = Ляховский А. А. Трагедия и доблесть Афгана. Alexander Lyakhovsky—Major General, General Staff of the Soviet Army. Served in OKSVA as an aide to the top USSR military adviser in DRA, Army General Varennikov. Many primary sources were first published in this book.
(JSTOR) Amin Saikal. The Afghanistan Crisis: A Negotiated Settlement?. The World Today Vol. 40, No. 11 (Nov., 1984), pp. 481-489. Published by: Royal Institute of International Affairs.
understanding the aftermath of the entire thing
This is even less explored and established than causes of the intervention. Also discussion about consequences goes into the gray area of 'modern politics' and may violate 20-yr rule of this subreddit.
Listing some of them:
Dissolution of USSR. While there is a general agreement that intervention in Afghanistan has strained Soviet Army and USSR in general, it is still hotly disputed how much exactly it influenced the USSR break up. My take - significant, but not critical factor.
Illegal drug trade (opiates, heroin) shot thru the roof over the years. While in early 80s Golden Triangle was world supplier, now it is Afghanistan. Per UN data, 83% of illicit heroin was produced in Afghanistan. See [2].
Middle Asian republics (which became independent after USSR dissolution) were destabilized by influx of weaponry, radical clerics and narcotics. All of them experienced militant insurgencies - some very serious, some mild. Large-scale civil war raged in Tajikistan. Islamic Movement of Uzbekistan operates from bases in Afghanistan. See [3,4].
Afghan Army withstood first serious tests (Navaz Tanai mutiny - Halq faction turned to opposition, attempt to take Jalalabad by united opposition). However, government forces has lost Khost and continued to be plagued by low morale, high desertion rate and frequent mutinies.
Najibullah government was alive and kicking until newly-independent Russian Federation cut off supplies in 1992. Most serious was lack of ammo and oil for heavy weaponry and air force. See [1], section "Aftermath".
Loss of Khost. Quite soon after withdrawal, city of Khost was lost again. It was blockaded by Jadran tribe and Haqqani forces in 1987. De-blocked during Operation "Magistral'" - last large-scale offensive of OKSVA in late 1987-early 1988.
A lot of equipment and buildings was transferred to Afghan army and government structures. Sadly, almost all of it was looted right away.
Jalalabad was the first Soviet garrison handed over to the DRA. The Soviet 66th Separate Motorized Rifle Brigade had been stationed there and took maximum effort to ensure that the garrison and its equipment was transferred correctly. The 66th left a three-month reserve of ammunition, fuel and food at the Jalalabad garrison. The garrison had barracks buildings, mess halls, steam baths and a hospital. The soldiers fixed everything that needed repair including the weapons and equipment that were going to be transferred to the DRA. Afghan inspectors from the Ministry of Defense test-fired all the weapons and drove the equipment before they accepted it. The soldiers cleaned the barracks and made up all the bunks with clean blankets and linen. The soldiers had to sleep outside the night before the turnover to keep the barracks spotless. On the morning of 14 May, 1988, the Afghan 1st Corps Commander signed for the garrison and the entire 66th Separate Motorized Rifle Brigade left Jalalabad by convoy heading toward Kabul and eventually home. The Afghans took over the garrison and striped it bare by that afternoon. Soviet televisions, radios, air conditioners, furniture and bunks were now for sale in the city shops. They even stripped the doors, windows and window frames from the buildings. Several days after this, the DRA 1st Corps Commander requested urgent resupply from Najibullah. He stated that the threemonth reserve of ammunition, fuel and food had not been left. The 1st Corps Commander had actually personally signed for it. The 40th Army learned from this sad experience. In the future, they insisted that an MOD official sign for property and material and they videotaped the entire transfer procedure of inspection and acceptance.
In all, the Soviets transferred 184 garrisons worth 699 million rubles and transferred government equipment worth 98.3 million rubles.
Sources
(UN report, PDF) - The global Afghan opium trade, 2011. Not to discuss current events, just to illustrate the trend. See Fig 1.
Spiegel - 'There Will Be Another War': An Islamist Uprising in Tajikistan, 2010. While this link breaks 20-yr rule, I've posted it here to show that Tajikistan is still unstable, with looming threat of civil war.
Farangis Najibullah, a radio reporter and expert on Central Asia, expresses what many are now thinking: That the Rasht Valley could become a "hotbed of Islamic resistance," which would destabilize the entire region.