India, Jan. 21 -- US President Donald Trump's renewed effort to annex Greenland has reopened a rift within the Republican Party, exposing tension over the extent of American hegemony. Began as a debate over Arctic security has evolved into a discussion about presidential power, military reach and the boundaries of loyalty within Trump's own party. The US already maintains more than 750 military bases around the globe, according to estimates tied to the Pentagon, leaving some lawmakers to wonder whether another roll of the geopolitical dice is worth the price.

Greenland has a population of nearly 60,000 is self-governing but still a part of the Kingdom of Denmark. Trump's assertion that the US needs to own the island has left Democrats an...