What was an effect of the open door policy? the united states would intervene to have access to foreign markets. the united states refused to trade with europe and japan. theodore roosevelt became a national hero?

The Open Door Policy is a term in foreign affairs initially used to refer to the United States policy established in the late 19th century and the early 20th century, as enunciated in Secretary of State John Hay's Open Door Note, dated September 6, 1899 and dispatched to the major European powers.