In the Terminator movies, we learn that Skynet sent a machine to the past to kill Sarah Connor in order to prevent John Connor from being born. in response, future John Connor sent Kyle Reese to stop the machine.
Well, we all know that the birth of John was a consequence of the Skynet-Resistance war. Kyle Reese was sent to the past; he protected Sarah, destroyed the machine, then slept with her and John was born.
So, why did Skynet send that machine if John was going to be born by Sarah's protector?
Did Skynet think Sarah herself would be a future threat to them and wanted to eliminate her because of this?
Did Skynet think Sarah will marry someone and John is their offspring? In other words, didn't the most intelligent thing (Skynet) know John Connor will be born if they send their machine to the past?