In both cases, they were razor-thin near misses. If either accident happened even once more, we absolutely would have either a radiological disaster or accidental nuclear war.
It's this sort of thing that makes me think maybe we shouldn't have any nuclear technology at all, the risks are just too high. Climate change is bad, but not as bad as burning our entire planet to the ground in under an hour, then poisoning it forever.
[1] https://en.wikipedia.org/wiki/1983_Soviet_nuclear_false_alar...
[2] https://en.wikipedia.org/wiki/1980_Damascus_Titan_missile_ex...