Iran battles on as war-planners calculate their rate of fire to avoid expending too many defensive missiles costing £1 mllion each - the deadly calculation is it's not sustainable

The US-Israeli war on Iran is reaching a critical stage as all sides carefully calculate their rate of fire in terms of missiles, bombs, drones and defensive munitions. Iran has clearly set out to drive for a war of attrition, a conflict involving endurance no matter the consequences and despite casualties that have soared past 1,000.

It also wanted to inflict as much damage to the economies of nearby Gulf States in a bid to exert leverage over them and it has hit homes, hotels and industrial sites., as it has taken lives too. It also has a limited number of missiles, rockets and drones and their largely low level of sophistication means they are sometimes difficult to combat. Low flying, cumbersome and slow drones might only require something as simple as a machine gun to bring down but wasting a £1million Amraam missile on them is unsustainable.

These were what was used by UK Typhoons and F-35B fast jets in the past couple of days over Jordan as they tricked incoming drones and brought them down. But an attack helicopter could have brought them down using perhaps £100 worth of machine gun rounds.

And the US and Israel have a finite number of defensive missiles so they will be trying economise as the tempo of battle slows. Plus - keeping the US aircraft carrier USS Abraham Lincoln operational in a threat of war, along with its three guided missile destroyers costs in the region of £8million a-day.

One thing is clear - that Iran does not have the same store of missiles as it had before five days ago when the war began and it is trying to slow its rate of fire. But at the same time the US and Israel do not want a protracted war they have to step back from if they expend their supplies of defensive missiles.

Western officials told the Mirror today that Iran is expected to be able to fire missiles for several days more but there are also fears that may be an underestimate. It is possible they could last for weeks. And even then the Islamic Revolutionary Guard Corps will resort to ‘asymmetric warfare’ of terror attacks in the region if it is able - and there are significant warnings it will.

And it is just possible Iran hopes it can outlast the rate at which Israel and the US plus other allies expend their interceptor missiles. This will, the regime hopes, force the US and Israel to stop the war, whilst all parties may be able to claim some sort of victory - Trump because he inflicted casualties and changed the Iranian regime, whilst hitting its ballistic and nuclear sites and Netanyahu because he can claim a pre-emptive strike on Iran.

Iran, however will likely claim simply that it stood up to the “Great Satan” as it calls America and at the same time attacked Israel. All of them are of course hollow and pointless victories, immensely costly in terms of human life, the global economy and world stability. Former Israeli military intelligence operative Danny Citrinowicz told the Mirror: “Iran started the war with between 2,000 and 3,000 medium range missiles, more than 5,000 short range missiles and I think between eight and 10,000 drones.

“But we don’t know how many launchers they have. They have to calculate how many they use as they want a war of attrition and have to regulate their use. They have to make sure they’re not going to exhaust their arsenal. I believe they are planning for a war of a couple of weeks, perhaps even more than that. They have been damaged but they still have the capacity to launch barrages towards the State of Israel and to use drones on the Gulf States.

“I believe the next level of escalation will be to attack the energy facilities in those countries - and I believe they hope we will run out of interceptor missiles. If we see that depleting in such a way that becomes harmful then maybe then Israel will end the war.”