The speed of the Taliban offensive raises questions of how long the Afghan government forces can stop the militants from reaching Kabul.
The Taliban has captured two major Afghan cities, the country's second- and third-largest after Kabul, and a strategic provincial capital further squeezing the embattled government just weeks before the end of the American military mission in Afghanistan.
The seizure of Kandahar and Herat on Thursday, marks the biggest prizes yet for the Taliban, who has taken 12 of Afghanistan's 34 provincial capitals as part of a weeklong blitz.
The capture of the city of Ghazni, meanwhile, cuts off a crucial highway linking the Afghan capital, Kabul, with the country's southern provinces, all part of a militant push some 20 years after US and NATO troops invaded and ousted the Taliban government.
While Kabul itself isn't directly under threat yet, the losses and the battles elsewhere further tighten the grip of a resurgent Taliban, who is estimated to now hold over two-thirds of the country and continues to press their offensive.
Taliban takes control of Herat
The Taliban has taken over Herat, Afghanistan's third biggest city, a government security confirmed.
"We had to leave the city in order to prevent further destruction," the security source told AFP on Thursday.
Earlier in the day, Taliban took over the police headquarters in the city.
On Twitter, Afghans were sharing reports of how Taliban has taken complete control of Herat — the 11th city to have fallen into the hands of the militants.
A member of the Herat uprising forces: “Herat has fallen. It’s been two hours it’s in the hands of the Taliban …”— Ali M Latifi (@alibomaye) August 12, 2021
Herat — about 150 kilometres from the Iranian border — is home to veteran warlord Ismail Khan, who for weeks has been rallying his forces to make a stand against the Taliban.
The Taliban also captured the strategic provincial capital of Ghazni near Kabul, in a weeklong sweep across Afghanistan just weeks before the end of the American military mission there.
Seizing Ghazni cuts off a crucial highway linking the Afghan capital with the country's southern provinces, which similarly find themselves under assault as part of a militant push.
As security forces retreated across the country, government sources told AFP on Thursday that Kabul has made an offer to the Taliban to share power in return for an end to fighting.
Reports say Ghazni's provincial governor and police chief made a deal with the Taliban to flee after their surrender.
Taliban video and photos purported to show the governor's convoy passing by Taliban militants unstopped as part of the deal.
Later Thursday, Afghanistan's Interior Ministry said the governor and his deputies had been arrested over that alleged deal. The officials could not be immediately reached for comment.
Taliban's weeklong blitz and government response
While Kabul itself isn't directly under threat, the loss of Ghazni, and now Herat, tightens the grip of a resurgent Taliban estimated to now hold some two-thirds of the nation.
Thousands of people displaced by the fighting have fled to Kabul and now live in open fields and parks.
President Ashraf Ghani is trying to rally a counteroffensive relying on his country's special forces, the militias of warlords and American airpower ahead of the US and NATO withdrawal at the end of the month.
However, the stunning speed of the offensive raises questions of how long the Afghan government can maintain control of the slivers of the country it has left.
The latest US military intelligence assessment suggests Kabul could come under militant pressure within 30 days and that, if current trends hold, the Taliban could gain full control of the country within a few months.
The Afghan government may eventually be forced to pull back to defend the capital and just a few other cities.
As security forces retreated across the country, Kabul handed a proposal to Taliban negotiators in Qatar offering a power-sharing deal in return for an end to fighting, according to a member of the government's team in Doha.
A second negotiator, Ghulam Farooq Majroh, said the Taliban had been given an offer about a "government of peace" without providing more specifics.
In Washington, defence officials appeared to be grappling with the spiralling situation but insisted that Afghan security forces were still holding their ground.
"What we're seeing, a deteriorating security situation, we've been nothing but candid about that," Pentagon spokesman John Kirby told reporters on Wednesday.
"But there are places and there are times, including today, where Afghan forces in the field are putting up a fight."