Did I miss something out??
They plan an expedition to that pyramid in Antartica, without any knowledge about who and when it was built. It looks like a normal research expedition at first, like a first expedition to the pyramids in Egypt.
But then when the team arrives at the abandonned village and the first ones descend to the pyramid through the tunnel, those staying in the village suddenly all have full auto G36C assault rifles with laser sight. How? Just how, and why do they have such military acsessoires, they couldn't know they get attacked by aliens. They don't visit a war zone, they visit Antartica. Or is the fear that there will be hostile concurrence that also wants to be the first one to discover the pyramid like when Bishop said "soon others will come"?