How did the geographic location of the US help it to “steer clear of permanent alliances” with European nations for many years?

The Louisiana Purchase (French: Vente de la Louisiane 'Sale of Louisiana') was the acquisition of the territory of Louisiana by the United States from France in 1803. In return for fifteen million dollars, or approximately eighteen dollars per square mile, the United States nominally acquired a total of 828,000 sq mi (2,140,000 km2; 530,000,000 acres). However, France only controlled a small fraction of this area, most of it inhabited by American Indians; for the majority of the area, what the United States bought was the "preemptive" right to obtain Indian lands by treaty or by conquest, to the exclusion of other colonial powers.[1][2] The total cost of all subsequent treaties and financial settlements over the land has been estimated to be around 2.6 billion dollars.

Japan's government is dictatorship.