I think the confident tone affected by the Iranians is because of something (slightly noticed out here) which happened over there last September: a well-coordinated, damaging drone-strike against Saudi oil facilities. Patrick Cockburn at once recognized that military history had undergone a quantum transformation:
Debate is ongoing about whether it was the Iranians or the Houthis who carried out the attack, the likely answer being a combination of the two, but perhaps with Iran orchestrating the operation and supplying the equipment. But over-focus on responsibility diverts attention from a much more important development: a middle ranking power like Iran, under sanctions and with limited resources and expertise, acting alone or through allies, has inflicted crippling damage on theoretically much better-armed Saudi Arabia which is supposedly defended by the US, the world’s greatest military super-power.
If the US and Saudi Arabia are particularly hesitant to retaliate against Iran it is because they know now, contrary to what they might have believed a year ago, that a counter-attack will not be a cost-free exercise. What happened before can happen again: not for nothing has Iran been called a “drone superpower”. Oil production facilities and the desalination plants providing much of the fresh water in Saudi Arabia are conveniently concentrated targets for drones and small missiles.
The Drone Strikes on the Saudi Oil Facilities Have Changed Global Warfare