War, boiled down to its most brutal calculation, is a business of accounting: “blood and treasure” in the horrible expression.
Cost calculations underpin warfare in terms of hard cash damage to economies and societies – what is called resilience.
Which makes the use of one of the US military’s largest non-nuclear explosive devices – the MOAB – to kill 36 jihadis in Nangarhar province , Afghanistan, somewhat baffling in military terms.
Each MOAB, or massive ordinance air blast – nicknamed the “mother of all bombs” – costs $16m (£13m) out of a total programme cost of $314m which produced about 20 of the bombs.
Crunched down – and in the most cold-blooded terms – that means the US military has expended some 5% of its stockpile of MOABs to kill three dozen Isis members at a cost of almost $450,000 per individual.
In comparison, a typical, general-purpose 450kg (1,000lb) bomb like the MK-8 used in numerous airstrikes in Syria in Iraq costs about $12,000.
Another point of comparison is the 59 Tomahawk cruise missiles fired a week before at the Shayrat airbase in Syria, which Washington has claimed as the source of the chemical weapons strike on Khan Sheikhun.
Those missiles will cost about $60m to replace, with each costing about $1m and delivering – combined – just over twice the tonnage of explosives of the single MOAB.
Until now, the MOAB had been something of a very costly white elephant.
Developed for the 2003 invasion of Iraq, unlike the JDAM-equipped bombs, the MOAB, which explodes just above the ground with massive force, had not been used in part because it is so specialised and for fear of civilian casualties from a weapon with such a substantial blast radius.
Thursday evening’s strike against what amounts to a handful of largely lightly armed Isis fighters in a crude tunnel system seems unlikely to change that assumption.