The driving force behind any such development is Donald Trump, his administration and somehow the Israeli government that seems strangely eager to encourage Iran to start working on nukes again.
We don't know what actually happened in the brain of the president. On a good day he is lying, corrupt and lazy. On a bad day he has obvious cognitive deficiencies. So we can't know if he intended to follow through on the attack or if it was just a show. We don't know how certain he and his people are about Iran attacking the drone.
His reason for stopping the attack was either transparent BS, or he was sleeping through the initial briefing when he authorized the attack in the first place, because there is absolutely no way that they realized only after the attack was in motion, that people would die.
The more likely reason he stopped the attack was he watched criticism of a possible attack on Fox News, right after he had authorized it, since there was a segment around that time where Fox News hosts were discussing how it would negatively impact his polling to start a war against Iran.
