SINGAPORE — President Trump’s eager embrace of Kim Jong-un of North Korea this week, on the heels of an acrid falling-out with Prime Minister Justin Trudeau of Canada, raised an obvious, if confounding, question: Why would an American president offend allies and cozy up to adversaries?

If there was an answer in Mr. Trump’s tumultuous week on the global stage, it may be that he disregards the traditional preoccupations of American foreign policy — power and values — in favor of a more narrow worldview shaped by his experience as a businessman.

“The theme that comes up, over and over, is money,” said Jeffrey A. Bader, a diplomat who advised President Barack Obama on China.

Mr. Trump’s bitter clashes with Canada and Europe over trade, as well as his solicitous courtship of North Korea’s brutal dictator, all reflect this mercantile perspective. In his transactional approach to foreign policy, considerations of financial profit or cost — often measured in ways that economists deem simplistic — can outweigh virtually any other consideration.