What has caused the emerging rift between the US and Europe regarding their approach to Ukraine?

Signs of a rift between the US and Europe became evident through statements from several US officials. Comments from the Secretary of Defense in Brussels, Vice President J.D. Vance, special Russia-Ukraine envoy General Keith Kellogg in Munich, and Donald Trump himself following his call with Vladimir Putin all contributed to this divide. These developments have effectively dampened hopes for US-Europe cooperation on Ukraine's future. The differing perspectives and strategic approaches have created tension in what was previously assumed to be a unified Western response to the Ukraine conflict, complicating the geopolitical landscape and potentially affecting Ukraine's security prospects.