After Trump became the 45th President of the United States, the United States not only provoked Sino-US economic and trade frictions and launched a "technological war" against China. European countries and the European Union, which are traditional allies of the United States, were also attacked indiscriminately, turning ordinary rifts in US-European relations into serious wounds and creating a "transatlantic change." Trump's "arrogant diplomacy" toward Europe has stripped away the "facade of friendship" presented to the world by the long-term alliance between the United States and Europe, showing another form of the United States after the decline of hegemony, and also made European allies experience the "chill" of cruel geopolitical competition. To what extent has Trump damaged relations between Europe and the United States? What is the reason for his behavior? What new changes have occurred in U. S.-Europe relations after Biden entered the White House? This book provides a comprehensive assessment of this change in transatlantic relations from multiple fields such as diplomacy, economy and trade, security, climate change, foreign aid, and geopolitics.