system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why hasn't anyone/won't anyone take militarized action to secure the Ukraine crash site and investigate, with so many countries having had citizens who died in the MH-17 incident?
gpt
There are a lot of politics involved, and very large consequences for any military unit violating another nation's borders.  Countries may not want to start a war for the sake of a few dozen people.

Additionally, military action isn't something that can happen overnight.  Supply lines need to be generated, mission parameters and rules of engagement formulated, and plans made.  By the time a mission arrived, there would be no remaining evidence of the incident.