The leaders of France and Britain are both due to meet with President Trump this week. Approaches previously tried with him may no longer work.

The visits come amid a rift between Trump and Ukrainian President Volodymyr Zelenskiy, whom Trump described as a "dictator", that has alarmed Kyiv's European allies, already reeling from a more aggressive U.S. posture on trade, diplomacy and even domestic European politics.

French President Emmanuel Macron was prepared to present a unified case for Europe when he arrived at the Oval Office on Monday, at a moment when transatlantic ties have rapidly deteriorated.