The situation after the lighting Taliban offensive and takeover in 1996 (Dostum = Uzbek, Massoud = Tajik):
“Northern Alliance” control 1996-2001 coincided with the part of Afghanistan home to its Tajiks and Uzbeks:
However, this time around the Taliban already hold much of the Tajik and Uzbek north in advance of the battle for Kabul. They hold half of the northern provinces in full, the other half in part, and the great majority of the northern provincial capitals. August 13th, 2021:
In only 8 days, the Taliban took control of 16 of Afghanistan’s 34 provinces and conquered 18 of its provincial capitals. This rout of ANDSF forces has opened the door for a Taliban siege of Kabul, as the insurgents now firmly control the majority of Afghanistan’s cities and districts
Aside from cutting off its traditional retreat, this also complicates the government’s ability to defend Kabul. Any defense would rely on Tajik troops, particularly the Commandos, but in many instances, these will be soldiers asked to fight for Kabul while their homes and families in the north are already under Taliban-aligned rule.
Since 2007, the jewel of US and Western military training missions in Afghanistan has been the Afghan Commando Corps or special operations forces, who comprise only 7% of Afghan National Army troops but reportedly do 70 to 80% of the fighting. But the Commandos have struggled to reach their target of recruiting, arming and training 30,000 troops, and poor recruitment from Pashtuns, the largest and traditionally dominant ethnic group, has been a critical weakness, especially from the Pashtun heartland in the South.
The Commandos and the professional officer corps of the Afghan National Army are dominated by ethnic Tajiks, effectively the successors to the Northern Alliance that the US supported against the Taliban 20 years ago. As of 2017, the Commandos numbered only 16,000 to 21,000, and it is not clear how many of these Western-trained troops now serve as the last line of defense between the U.S.-backed puppet government and total defeat.
The Taliban’s speedy and simultaneous occupation of large amounts of territory all over the country appears to be a deliberate strategy to overwhelm and outflank the government’s small number of well-trained, well-armed troops. The Taliban have had more success winning the loyalty of minorities in the North and West than government forces have had recruiting Pashtuns from the South, and the government’s small number of well-trained troops cannot be everywhere at once.
The Russians — who were a weak but principal backer of the Northern Alliance before the US took over in 2001 — have definitely taken note:
Taliban militants have taken control of Afghanistan’s borders with Tajikistan and Uzbekistan, Russia’s Kommersant daily reported on Wednesday, citing Defense Minister Sergei Shoigu, heightening security concerns for Moscow.
Shoigu said the Taliban have promised not to cross the border, but that Moscow would continue holding joint drills with its allies in the region.
Taliban control of the Uzbek and Tajik border also means that this time there can’t be a trickle of aid, at least not over land and from the north.
A more detailed ethnic map: