In January, President Donald Trump returned to the White House, facing a world that is arguably more complicated than when he left the building four years earlier. The war in Ukraine, which will enter its fourth year in February, will take much of Trump’s time as he begins to craft and sell a detailed plan to cease the fighting and negotiate a peace settlement that Ukrainian President Volodymyr Zelensky and Russian President Vladimir Putin can live with. China, the aspiring hegemon that seeks to displace the United States as the world’s foremost power, will be a constant challenge for Trump’s administration as it was for former President Joe Biden’s. U.S.-European relations will be a challenge as well, thanks to Trump’s infatuation with tariffs as a tactic to extract economic concessions, as well as the president’s commitment to decadeslong wariness watching Uncle Sam carry the security of the entire continent on his back.