[quote=@Assallya]
Well... I don't remember a giant fortress called Arsenal Gear crashing into New York harbour five years ago so I say give the man some creative license *lol*
[/quote]

You're missing the point. MGS always had a backdrop of actual wars and social atmospheres for its games, and played off of them, even if the Big Shell incident was fictional.
For this to work, the GM needs to create an entire fictional war in the Ukraine, including the events and motivations behind each side, what their goal is, who's doing what and where, etc.