The fighting around three major Afghan cities in the south and west– Herat, Lashkar Gah and Kandahar – intensified as Taliban militants sought to seize them from government forces.
The Taliban have made rapid rural gains since it was announced almost all foreign troops would go by September.
But the fate of these key cities could be crucial amid fears of a humanitarian crisis and how long government forces will be able to hold out.
The fundamentalist Islamist militia is already thought to have captured up to half of all Afghanistan’s territory, including lucrative border crossings with Iran and Pakistan, but it has yet to take a provincial capital.
In Lashkar Gah, heavy fighting continued inside the city on Sunday.
Insurgents were reportedly only a few hundred metres from the governor’s office on Saturday – but had been pushed back by nightfall.
Flights at Kandahar airport were suspended on Sunday after Taliban rockets struck the complex before dawn, causing some damage to the runway.
Afghan and US air strikes have reportedly targeted Taliban positions and government forces say they have killed dozens of militants.
Afghan special forces have been deployed in the economically important city of Herat, and the situation appeared more stable on Sunday.
Afghan troops are fighting alongside the veteran warlord and anti-Taliban commander, Ismail Khan, who has mobilised citizens to take on the militants.
A guard outside a UN compound near the airport was killed on Friday in what the UN described as a deliberate Taliban attack.
US troops and their Nato and regional allies forced the Taliban from power in November 2001.
The group had been harboring Osama Bin Laden and other al-Qaeda figures linked to the 11 September 2001 attacks in the US.
But despite a continued international presence, billions of dollars of support and training for the Afghan government forces, the Taliban regrouped and gradually regained strength.
In February 2020, then-US President Donald Trump and allies agreed to formulate a deal with the Taliban on the withdrawal of international combat forces.
This year, President Joe Biden announced the withdrawal would take place by September.