Both these accidents happened over the waters edge or very near it. IF a ship was positioned under known flight paths couldn't a larger missile be used instead of the SA or stinger type. Maybe an intermediate size one....
Or as I suspect there might be someone with no ego but extreme survival traits that has figured out a way with either timing device, GPS or barometric trigger to bring planes down over water, making identification of source very difficult and that the object isn't only terror but to cripple the airline/travel/international business activity of the the infidel.
Just odd that the weird ones happen over water. Of course they ARE weird cause they happened over water and therefore difficult to assess fully.