

Also the US already has a military base in Greenland and has for many decades. In fact, they used to have dozen or so during the Cold War. And because the area is apparently such vital importance to the defence of the US, they currently have… 150 soldiers stationed there.
In the one base they have kept.
Very, very important location. Vital for defence.

Any temperature below somewhere around 60F/15C is “deadly cold”, as in your survivability depends entirely in how well you are clothed as you will eventually die of hypothermia otherwise, the only variable being how long it takes. Kinda like how you can get a 3rd degree burn with 44C water, it just takes 6 hours.
-12C really isn’t all that cold - lowest temperature in northern Finland this winter so far has been -42,8C / -45F - but it is a temperature where you will need to pay some attention on how you dress for it. For me, it’s around (-10 to 15c depending on the wind) where I’ll put on long-johns in the morning and add a sweater instead of just having a t-shirt under my jacket.