Days ago US forces in Afghanistan warned of the risk of suicide bombing in or around Kabul Airport. A major explosion has occurred in the last few hours - details are unclear. Here's a report.
The US Government would already be aware of the risk that low flying passenger transport aircraft might be shot down landing or taking off from Kabul Airport.
The Taliban have not yet shot down US or other military transport aircraft carrying refugees from Kabul Airport due to the Taliban’s deal with the US Government. This deal is set to end in a week, on August 31.
The Taliban are not a monolithic totally disciplined army, but many tribal groups that have been given the “Taliban” label, with their own agendas. Also non-Taliban, Islamic terrorist groups, already in Afghanistan, may have their own ideas. Some groups may ignore the Taliban-US deal and explode bombs or fire on aircraft before the August 31 deadline, aka “redline”.
The US and other transport aircraft can be seen dropping flares when leaving Kabul Airport to draw off Taliban or terrorist shoulder fired heat seeking missiles.
The Taliban are aware that the aircraft are not safe from much more common RPG7 unguided missiles as the RPG7 missiles cannot be drawn off by flares and may be unjammable.
Also the Taliban would be aware their heavy (50 calibre up) machineguns can shoot down aircraft. Such machineguns (up to 14.5mm) and frequently mounted on pickup trucks, were made in Russia and sold through many middle men.
But the majority of the heavy machineguns are US made 50 calibre M2 Brownings gifted by the US to the Afghan Army who, in turn, gifted them to the Taliban, over the last few weeks. These may be mounted on pickups or the many Humvees captured by the Taliban or Humvees gifted by the Afghan Army to the Taliban.