The president said it would come free if Canada decided to join the United States.

US President Donald Trump said that Canada could be included in his proposed "Golden Dome" missile defense system at "zero cost", if it agrees to become the "cherished 51st state" of the United States or pay $61 billion to take part in the project.

King Charles III will deliver a speech to Canada's Parliament on Tuesday, which is expected to support the country's sovereignty in the face of President Trump's annexation threats. Why it matters: Charles' visit comes as American-Canadian relations have splintered because of Trump's repeated annexation threats and tariff policies.