Last week's exchange that saw each country expel a diplomat was called a "spat"—but really it was the latest volley in a low-heat diplomatic conflict that's been simmering for years. Every new twist, from takeovers to arrests, from allegations of election interference and threats of retaliation, only makes the next more likely.How did China and Canada end up here? What have we learned in the past few months about just what China is trying to do in this country? What steps has our government taken to protect our democracy from outside interference? And what should we expect if China decides to retaliate?GUEST: Stephanie Carvin, former national security analyst, Associate Professor at the Norman Paterson School of International Affairs, author of Stand on Guard: Reassessing threats to Canada's National Security