The US GBU-43/B bomb detonates in the air and is said to create a blast wave for a mile in every direction. 
The US military has just dropped its largest conventional (that is non-nuclear) bomb for the first time in combat, on Afghanistan’s eastern province of Nangarhar. 
The GBU-43/B Massive Ordnance Air Blast Bomb (MOAB) – or, in military speak, Mother of All Bombs – was launched on Thursday. 
The target was said to be a network of tunnels operated by the so-called Islamic State in Achin district. 
As a non-nuclear weapon, use of the MOAB does not necessarily require approval by the US president. 
It is a huge weapon – a 30ft (9m), 21,600lb (9,800kg), GPS-guided munition that is dropped from the cargo doors of an MC-130 transport plane and detonates shortly before it hits the ground. 
The MOAB falls from the aircraft on a pallet, which is then tugged aside by a parachute allowing the weapon to glide down, stabilised and directed by four grid-like fins. 
Its principle effect is a massive blast wave – said to stretch for a mile in every direction – created by 18,000lb of TNT. 
The bomb’s thin aluminium casing was designed specifically to maximise the blast radius. 
The « bunker-busting » bomb is designed to damage underground facilities and tunnels. 
The weapon was developed for use in the Iraq war – at a reported cost of $16m (£13m) each – and was first tested in 2003, but never used in action – until now. 
And yet, the MOAB is not the US military’s heaviest non-nuclear bomb. 
That distinction belongs to the Massive Ordnance Penetrator, or MOP, an even bigger bunker-buster which weighs a colossal 30,000lb. 
Russia has developed its own massive conventional bomb, nicknamed the Father Of All Bombs. The FOAB is a kind of fuel-air bomb, technically known as a thermobaric weapon. 
Thermobaric bombs generally detonate in two stages: a small blast creates a cloud of explosive material which is then ignited, generating a devastating pressure wave. 
A significant part of the effect of weapons like the MOAB is said to be psychological – to instil terror by the massive force of the blast. 
Its development followed the use of similar weapons including the BLU-82 Daisy Cutter, a 15,000lb bomb designed in part to flatten a section of forest to carve out a helicopter landing pad. 
The MOAB was developed by the Alabama-based aeronautics company Dynetics.






