I recall I watch in the news when I was young.
Guys, remember in 1987 when a German teenager ride a Cessna plane from then West Germany and landed at Red Square, Moscow.
Russians air defence were at their best combat readiness during the time of Cold War,
their air defence radar, 3 SAM divisions and 2 interceptors actually do pick up the plane,
but somehow, due to poor co-cordination and mis-communication, the plane manage to bypass their defense and landed at the very heart of the Iron Curtains.
After this incident, a lot of high ranking Soviets officers were sacked, demote or transfer to Serbia.