Answer;
-the decreasing neutrality of the U. S. in World War I.
Step-by-step explanation;
-There were several reasons why the United States gave up the policy of neutrality to enter World War I. Two of the primary reasons had to do with threats due to the offensive tactics from the Germans.
-Under President Woodrow Wilson, the United States remained committed to neutrality during the early years of World War I. The Germans began using U-Boats in the Atlantic Ocean. The Atlantic was frequently used to transport passengers and cargo on British and American ships. The Germans bombed several ships and Americans were killed. Despite this, the United States remained neutral and sought to negotiate with the Germans.
-When Germany began using submarines to sink Atlantic shipping, the Americans were outraged since their ships were being targeted as well. The sinking of the Lusitania in 1917 was the final straw and probably the most compelling reason that the U.S. entered the war. Finally, there was the issue of the Zimmerman Note.