Definition: In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Try to find the best answer that is most likely to fill in "_". Note that the URLs in the text have been replaced with [Link].
Input: (CNN) -- Iran's supreme leader took verbal jabs at the United States Saturday in his first public reaction since the United States accused Iran of plotting to assassinate the Saudi ambassador to Washington. Ayatollah Ali Khamenei labeled the allegations "meaningless and absurd." "They (the U.S.) want to isolate Iran," Khamenei said over chants of "down with America" in a speech before thousands in the western Iranian city of Gilangharb. Also, an Iranian official said claims by the United States that a high-level U.S. diplomat had met Wednesday with an Iranian counterpart over the plot were untrue. "There were no kinds of negotiations between the two countries, and there was not such a contact," said Alireza Miryousefi, press secretary for the Iranian Mission to the United Nations.NEW: Scholar says plot does not fit Quds Force "M.O."Ayatollah Khamenei calls the U.S. allegations "absurd"Iranian diplomat: U.S. claims of a meeting with Iran are not trueThe U.S. alleges Iran was involved in a plot to kill a Saudi official in the United States 
 Question:"Doing so on _ soil is unmistakably an attack on the United States, not on Saudi Arabia."

United States