The initiative received a boost in recent weeks when US President Donald Trump offered to provide crucial backup support for a European reassurance force in Ukraine. This has given rise to some fundamental questions over the nature and goals of any future reassurance force. In the final analysis, what is the Coalition of the Willing actually willing to do in Ukraine? The biggest question of all is whether European troops in Ukraine would be permitted to fight back if attacked by Russia. At the same time, troops from the Coalition of the Willing could boost the Ukrainian military in meaningful ways.