The worlds of geopolitics and international diplomacy are currently focused on two seemingly unrelated but telling case studies: Greenland and Ukraine. Both highlight the head-spinning unpredictability of US President Donald Trump, leaving European allies scrambling to anticipate Washington’s next moves.

Europe Faces a Rollercoaster

European capitals are grappling with the challenge of aligning US policy with European interests, amid what many diplomats describe as a rollercoaster White House. Officials privately admit that each day brings new uncertainties, with little clarity about the direction of US foreign policy tomorrow—or next week.

This week, the contrasting developments in Greenland and Ukraine illustrate the complexity: outwardly, the two issues point in very different directions, yet both reflect the same underlying unpredictability of Trump’s administration.

Greenland: Sovereignty vs. Strategic Interest

Over Greenland, seven European leaders—including UK Labour leader Sir Keir Starmer—issued a joint statement emphasizing that Greenland’s future should be decided by Greenlanders and Denmark, and that US designs on the territory are counterproductive.

“We are on the same side, but Greenland’s future is for Greenlanders to decide,” the statement diplomatically stressed.

Despite the tone of dismissiveness, European diplomats acknowledge the need to take Trump seriously, given the US president’s insistence that Greenland is of strategic importance to American security and Arctic interests.

Ukraine: Steps Toward Security Guarantees

Meanwhile, in Ukraine, European diplomats report cautious optimism that the US has committed to a more active role in securing a long-term peace in Kyiv. For years, Europe has sought a robust US commitment to stability in Ukraine, and sources indicate that the presence of Trump envoys Steve Witkoff and Jared Kushner at the Coalition of the Willing meeting in Paris marked a significant shift in US engagement.

A preliminary document outlines what is being called “robust security guarantees for a solid and lasting peace in Ukraine”, including a US-led ceasefire monitoring and verification mechanism. This would rely on America’s advanced ISR capabilities—intelligence, surveillance, and reconnaissance—using drones, satellites, and other modern military tools.

While the exact scope of US involvement remains unclear, Europe views this development as a potentially pivotal step toward stabilizing Ukraine. However, major uncertainties remain:

• Can peace be secured without territorial concessions?
• Would Ukraine agree to compromise?
• How many US troops, if any, might be deployed on the ground?
• What is the long-term sustainability of such military and financial commitments?

European Security in the Trump Era

For European leaders, the challenges go beyond short-term decisions. They must consider whether the Trumpian approach is a temporary anomaly or a signal of an ongoing unpredictable US foreign policy.

“A secure Ukraine is a secure Europe, and a secure Europe is a secure UK,” one Whitehall source told me.

This reality highlights the interconnectedness of European and American security, while underscoring the difficulty of planning for a future shaped by unpredictable US leadership.

The Big Question: What Comes Next?

For now, Europe—and indeed the world—is left asking: what will the White House say or do next on Greenland and Ukraine? The unpredictability of Trump’s administration has made it clear that allies must expect sudden, dramatic shifts in policy, with global consequences.