Ukrainian President Volodymyr Zelensky has tailor-made his messaging to appeal to President Trump’s priorities.

Alarmed that U.S. security priorities lie elsewhere, a group of European countries has been working on a plan to send troops into Ukraine to enforce any peace settlement.

Like an object floating upwards yet still underwater, the bare, vague bones of a peace plan for Ukraine are taking shape.

Trump’s recent moves, including a conversation with Putin and a demand for Ukrainian mineral rights, are worrisome signs for ...