It is worth reviewing the KAL007 incident to understand why you see this kind of reaction. The USSR was doing a missile test, the US was flying a surveillance

It is worth reviewing the KAL007 incident to understand why you see this kind of reaction. The USSR was doing a missile test, the US was flying a surveillance plane just outside Soviet airspace, and just prior to that the US had been deliberating flying planes directly toward Soviet airspace only to turn them around at the last moment. Reagan had been talking tough and the USSR military leaders thought he might actually order a preemptive strike. Then KAL007 takes off from Alaska with its autopilot incorrectly configured, flies right into Soviet territory, and Soviet air defense had to decide if this unidentified plane was the US military finally being bold enough to fly right into their space. When KAL finally contacting Japanese ATC they were told to ascend, which to the Soviet fight pilot sent to intercept looked just like an evasive maneuver. The plane was shot down with no survivors, killing a member of Congress (just imagine how easily the situation could have escalated from there if Reagan really was as out of control as the Soviets thought). So yeah, better safe than sorry when you have a tense moment in between two hostile, nuclear-armed nations. I would rather see a bunch of travelers deal with the inconvenience of cascading delays than see some US air defense system shoot a plane out of the sky.