An article by Nic Robertson, International Diplomatic Editor, posted on CNN’s website yesterday, notes that earlier this week, Taliban militants sauntered up to the gates of Mazar-i Sharif, Afghanistan's fourth largest city.

The last time the Taliban controlled the city was 20 years ago.   Now, the militants are back at the city gates once again. 

One by one, the Taliban militants have been taking over areas in a number of provinces in northern Afghanistan in recent weeks. The Taliban movement says it has taken control of 90 districts across the country since the middle of May.  Some were seized without a fight.

The UN's special envoy on Afghanistan, Deborah Lyon put the figure lower, at 50 out of the nation's 370 districts, but told the Security Council on Tuesday she feared the worst was yet to come.

The dire warnings come just two months after President Joe Biden announced that US and NATO troops would withdraw from Afghanistan by September 11.

To-date, the Taliban militants have taken districts  in Faryab province, in Balkh province, and in the provinces of Kunduz and Takhar. 

Already the country's diverse ethnic communities, from Hazaras to Uzbeks to Tajiks, are reportedly looking to defend themselves from the onslaught of Taliban attacks.

Ata Mohammad Noor, a former warlord and ex-governor of Balkh, the province home to Mazar-i Sharif, has urged his predominantly Tajik group Jamiat-e-Islami-- which fought the Taliban as part of the Northern Alliance in the 1990s -- to take up arms again.

On Monday night the Taliban militants captured the important border town of Sher Khan Bandar, Afghanistan's main crossing into Tajikistan.  Earlier in the day, top Tajik government officials had reportedly met to discuss concerns about the growing instability next door.

There is no indication that the Taliban intend to take their fight north of the border, but in the past Tajikistan has been a vital conduit for supplies flowing to the militants' northern enemies, the article says.

America's drawdown reportedly seems to be the gamechanger.  The article notes that the Taliban have been beaten back several times in recent years, notably from Kunduz in 2015.  The Taliban reportedly captured it briefly before US airstrikes were called in.  Civilian casualties were high but the militants were driven out.

The militant group has never been able to withstand the heavy US and NATO air assaults backing Afghan ground forces, but now the US and NATO are leaving, so is much of the threat of sophisticated and sustained air power.  And the Taliban are well aware of this.