I wouldn't be surprised if it was 25 suicides and they were using this as a cover-up
I was thinking a bit along the same lines, but more like - some of the deaths may well have been suicides with no direct evidence to prove it. Also, some of the Marines may be depressed and couldn't care less - consciously or subconsciously - whether their risky behavior ends in death. Yet another possibility likely is that condition (not sure if it has an official name) where people who have experienced extreme high-risk situations need to repeat events that will produce the same sensations. I think those are further broken down to some who crave the same feelings, and others who are more likely depressed and can't feel anything at all, and may be trying to break through that.
I don't think I'm explaining this very well, I'm in need of some coffee I believe. I'm also no expert, but someone here is (warning, maybe?) and I'd be interested in his thoughts on the subject, whoever it is...
I'm also somewhat wary about the story, as in - what was the point of it? Was it simply an informational report, or worse, ie: "War is not as dangerous as everyday life?"