As JD Vance touched down in Greenland, the Trump administration received an unlikely endorsement for the US’s first potential territorial expansion since 1947: Vladimir Putin. Speaking at an Arctic policy forum in the northern Russian city of Murmansk on Thursday, Putin presented a more comprehensive case than any US official yet for Donald Trump’s plan to annex Greenland, crafting a historical argument that sounded suspiciously convenient in terms of Russia’s own territorial designs on Ukraine. The US’s plans to take control of Greenland “may surprise someone only at first glance, and it is a deep mistake to believe that this...