The USA has, by any measure, a veritable monopoly of coercive force on the world stage. Their military expenditure is more than the next 15 countries combined.

The USA has, by any measure, a veritable monopoly of coercive force on the world stage. Their military expenditure is more than the next 15 countries combined. This means they have the capability to enforce their will globally to a significant extent. In an arena such as geopolitics, justice is the will of the stronger, no holds barred. This makes the USA arguably the primary concern in geopolitics, the ring you need to kiss to do anything on that stage. Keep in mind that “claimed” may be referring to the sense of “won” rather than “stated”. From that perspective it’s not too much of a stretch to call them the world leader, but that does ignore the fact that leadership implies the will to lead and to a significant extent the requisite wisdom and skills.