America’s role in the world is changing. If this wasn’t obvious before, it should be now, following President Donald Trump’s efforts to take over Greenland and his visibly strained relations with traditional allies in Europe and elsewhere.

But how much will the world change if America’s stance is different?

Some scholars of international relations argue that because Washington has been central to global governance for so long, Trump’s “America First” turn – suggesting isolationism on some issues and unilateral action on others – spells the end of the international order as we’ve known it.

The most pessimistic analysts caution that the era of “Pax Americana,” or the long period of relative world calm since World War II due to U.S. leadership, is coming to a close. They forecast a turbulent transition to a more chaotic world.

This view may well prove correct in the long run. But it is too early to say with confidence. As a scholar who studies U.S. foreign policy, I see some grounds for optimism. The world can become a more just, stable and secure place despite the diminishment of American leadership.

For the remaining three years of Trump’s presidency, all bets are off. Trump is famously difficult to predict. That world leaders genuinely believed in recent weeks that the United States could invade Greenland – and still might – should give pause to anyone who thinks they can foretell the remainder of Trump’s second term.

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