One way that the British government carried out the policy of mercantilism was by (4) requiring that most colonial trade occur within the British empire. This was the basic policy of colonial mercantilism, where colonies such as the United States could only trade with Great Britain, and was banned from trading with other colonial superpowers, such as the Netherlands, France and Spain.
The newspapers that used yellow journalism reacted when the USS Maine exploded in Cuba in 1898 by blaming Spain for the explosion. The encouraged the United States to declare war on Spain.