The civilian casualty rate plummeted as a result of the new rules, which were brought in because commanders believed the civilian deaths were driving the Afghan people into the arms of the Taliban.

The rule change specifically prohibited strikes on buildings in all but the most extreme circumstances, because such attacks were most likely to hurt civilians.

The US will not comment on whether the rules have changed. However the Bureau has recorded at least 73 strikes on buildings in Afghanistan – out of 1,346 in total – since it began monitoring reports of US air attacks in Afghanistan following the end of combat operations in December 2014.

One series of strikes in November this year hit several buildings, killing 32 civilians. Unama says questions remain about whether the attacks were acceptable under international law.

Resurgent Taliban versus hamstrung Afghan forces

The US and its allies from Nato and other international partners are faced with a dilemma. The Taliban is resurgent and the Afghan forces, hamstrung by poor logistics, leadership and corruption, are struggling.

They have needed more and more international support but NATO’s Resolute Support Mission (RSM), led by the US, has seen its numbers dwindle since the end of combat operations in December 2014. This means the Americans are trying to fight an insurgency largely from the air.

US air attacks have increased by around 50% since 2015 – largely thanks to a change in rules in June that meant the Americans could specifically target the Taliban. Before then only al Qaeda and Islamic State could be specifically targeted.

A surge in the number of American strikes from July through to October appeared to be the result of the US trying to cut down the Taliban and keep the Afghans holding the line.

Air support is crucial in the fight against the Taliban. Strikes stop the insurgents from massing in large numbers because such formations present too easy a target. Strikes are also essential to save soldiers pinned down in insurgent attacks.

Strikes in civilian-populated areas

With much of Afghanistan’s fighting last year taking place in civilian-populated areas, air attacks also carry a considerable risk of civilian harm.