Leaders from across Europe gather at an English country mansion on Thursday for a summit clouded by worries about whether the United States would remain a reliable ally if Donald Trump secures a second presidency.

Newly elected U.K. Prime Minister Keir Starmer is welcoming some 45 heads of government to discuss migration, energy security and the threat from Russia as he seeks to restore relations between the U.K. and its European Union neighbors, four years after their acrimonious divorce.