Support for the war in Afghanistan is less than 20 percent, making the longest U.S. military conflict the least popular, a CNN poll released Monday indicated.

Results of the CNN/ORC International survey also indicates a majority of Americans would like to see U.S. combat troops leave Afghanistan before the December 2014 deadline.

Only 17 percent of Americans say they support the 12-year-long war, the poll indicated. Opposition is at 82 percent.

"Those numbers show the war in Afghanistan with far less support than other conflicts," CNN Polling Director Keating Holland said. "Opposition to the Iraq war never got higher than 69 percent in CNN polling while U.S. troops were in that country, and while the Vietnam War was in progress, no more than six in 10 ever told Gallup's interviewers that war was a mistake."

Nearly all U.S. troops are to be out of Afghanistan by this time in next year; however, just more than half of Americans said they'd rather see U.S. troops withdrawn sooner, the CNN poll indicated. Only 24 percent said America should still have boots on the ground in Afghanistan after the deadline.

About 2,300 U.S. troops have been killed in Afghanistan since the war began in 2001.

Results are based on a nationwide phone survey with 1,035 adults conducted Dec. 16-19. The margin of error is 3 percentage points.