Answer:
the answer is a hope it kinda helps
The single main event that <span>caused the United states to become involved in world War 1 was the German sinking of the ship the "Lusitania," which contained many American citizens. </span>
Arab nations of the Organization of Petroleum Exporting Countries (OPEC) imposed an embargo against the United States and its allies as a response to the U.S. decision to provide military support to the Israeli in order to give the Israel a jump start in the post-war peace negotiations.
I would say BOTH primary AND secondary,
hope this helps :)