Yet every one of those problems becomes more difficult to confront if the country is ripped apart by political divisiveness so bitter that politicians act (and citizens vote for politicians who act) as if they thought the gravest threat to the country came not from external adversaries, but from other citizens who voted for the other party. First, domestic dysfunction can hobble the U.S. government directly, perhaps by leaving political leaders so focused on internal problems that they lack bandwidth to address global issues or perhaps by saddling them with governmental paralysis that freezes the engine of foreign policy.