LONDON — The day after Benjamin Netanyahu's cartoon representation of an Iranian nuclear bomb went viral on the Internet, opinion was divided on whether the Israeli prime minister's headline-grabbing prop was a stroke of presentational genius or a cheap gimmick.

Benjamin Netanyahu, Prime Minister of Israel, points to a red line he drew on a graphic of a bomb while addressing the United Nations General Assembly on September 27, 2012 in New York City.

With the aid of a Wiley E. Coyote-style cartoon bomb and a red marker pen, Mr. Netanyahu sought to underline the threat posed by Iran on Thursday to members of the United Nations General Assembly.