Book excerpt: German-American relations have become interesting again. U.S. President Donald Trump’s lukewarm policy toward Europe has ensured that the relationship between Berlin and Washington is once again regarded as an important field of scholarship within global politics. And yet it was only a few years ago that German-American relations seemed to take second place to transatlantic relations in general, and the European Union (EU)–USA relationship in particular. The advent of Donald Trump as US President in January 2017 has made all the difference. Trump’s difficult personal relationship with German Chancellor Angela Merkel, and his denigration of everything the Western world – including the USA itself – has stood for since 1949, have given a new significance to German-American relations in practice and theory. This volume offers an empirical and conceptual analysis of German-American relations in the 21st century and highlights the serious and perhaps unprecedented challenges the two countries face at present. The authors discuss a number of aspects of the current, much more fragile state of German-American relations from different perspectives. This book was originally published as a special issue of the journal German Politics.