User blog comment:SSDGFCTCT9/Story (Mk.II)/@comment-1427137-20100710214839

Western countries got involved by not minding their own business, but also because of multiple threats. The US, being a key military force, couldn't just sit there as two behemoths conquer all of Asia, and to further extents after that, now could it? Canada gets into it a similar way, basically following the US's lead, and Quebec soon after.

The EU, being allied with Germany, notices the threats of the Soviet Union with its borders on Germany and Finland, and the Mongols quick invasion of Turkey could reach European territory quickly.

I need to be more specific about these things, or, you know, not forget to say them, lol.