The number has jumped 10 points since February, when 66 percent of Americans said they were worried about military conflict.

Although Americans are concerned about a number of national security threats, a strong plurality (41 percent) believe that North Korea currently poses the greatest immediate danger to the United States, emerging as a more urgent concern than ISIS (28 percent) or Russia (18 percent), according to the poll, which was conducted online from July 10 through July 14.