>>credit+(OP)
Start from the beginning.[1] The point is there is no good reason for the US to leave one operational, defeating the whole purpose suggested by those claiming the US did it, and worse, leaving open the possibility of a major political victory for Russia. This is a big hole in the theory that the US did it. There may be good reasons for other parties to leave one operational though. You can speculate.
[1] https://news.ycombinator.com/item?id=34712780