Larry Kudlow accused Canada of making polarizing comments about the United States' trade policy, and said that President Donald Trump had to pull out of a joint statement because the Canadian prime minister has "stabbed us in the back." 

The future of military alliances, the fight against climate change and even free trade are all expected to be on the agenda as Trump sits down with his NATO and G7 counterparts.

Justin Trudeau heads to Europe this week for the NATO and G7 summits, where global leaders are trying to figure out exactly how the world works now that U.S. President Donald Trump is at the table.