As Donald Trump strengthens his lead in the race for the Republican presidential nomination‚ some U.S. allies are worried about an American turn toward isolationism‚ a shift that would reflect an electorate largely focused on domestic issues. That was shown in polling in Iowa where Trump scored an overwhelming victory on Monday‚ with foreign policy the top issue for just one in 10 participants in the state's caucus‚ according to a poll by Edison Research. That compared to four in 10 who...