Imperial powers use policies such as taxation, trade, governmental structures, and education. For example, in America, the British Parliament taxed U.S. products heavily (leading to the famous revolt at the Boston Tea Party). Imperialist nations can also use trade as a bargaining chip by lowering transaction costs at their own trading posts and taxing goods at others. For example, under the Navigation Acts, the U.S. colony could trade only with Britain, at which point Britain would trade the goods with other nations. Finally, imperialist nations can use a military presence in their colonies in order that individual persons loyal to the imperialist nation wield power in the colonies. Schools, too, while generally understood to be a liberating force, can in fact be a tool of imperialist powers. Britain famously set up western schools in their colonies in India, and even locals began to see a western education as the key to better themselves in order to revive their native Indian heritage.