Canada has been boosting its forces in the Arctic in the face of new threats - and US concerns.

The debate around the Arctic is becoming hotter than ever as US President Donald Trump insists Greenland should become part of the United States. Security, shipping routes and mineral wealth are all in the mix.

An unusually brutal winter storm is set to pummel more than 160 million Americans from Friday, as a stretched "polar vortex" sends a devastating blast of Arctic air, bringing heavy snows and freezing rains.

U.S. President Donald Trump wants to buy Greenland as he says it is the only way for the United States to secure its defence. Denmark and Greenland, an autonomous territory, refuse and say any concerns Washington has can be addressed via their existing defence agreement.

With the windchill, the temperature in New York City could feel like 8 degrees.

A big concern is Texas, where cold temperatures threaten to ice oil-and-gas fields and wreak havoc on the power grid.

Rising Arctic temperatures and melting sea ice could be causing cold air to flow into the Northern Hemisphere. But not all scientists agree.

Forecasters are warning of a sprawling winter storm that's predicted to spread a mess of ice and snow over a 2,000 mile stretch of the nation.