remember the first time you did that mission, read the title and thot " what the hell is that?" i have the answer.
Time magazines do indeed come in handy. Phnom Penh is the capital of cambodia, and during the vietnam war, a large scale killing took place, mostly by helicopter.
Tommy essentially recreates that.
Note: i got my info from a time magazine about how some guy was on trial for the killings in phnom penh and wikipedia on exactly what the hell phnom penh is. this may not be totally accurate.