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Public criticisms of the war in Afghanistan have reached new highs in the latest ABC News/Washington Post poll, with two-thirds of Americans saying the war hasn't been worth fighting and half saying it's failed to contribute to the country's long-term security.

Nonetheless, with the bulk of U.S. combat troops set to leave by the end of 2014, the poll finds that most Americans would rather have some remain in place for training and counter-insurgency purposes than to remove all U.S. forces.

See PDF with full results and charts here.

Overall, considering the costs versus the benefits to the United States, 67 percent now say the war in Afghanistan has not been worth fighting, a new high (albeit by a single percentage point) in 21 ABC/Post polls to ask the question since early 2007. For the first time that numerically exceeds the most who said the same about the war in Iraq, 66 percent in April 2007.

Just 43 percent say the war has contributed to the long-term security of the country, down by 8 points since March, to the fewest in five polls since mid-2010. It's the first time more people have said the war has not contributed to U.S. security than say it has.

Additionally, just 17 percent say the war has contributed "a great deal" to long-term security. Both these, again, are numerically lower than the lowest ratings for the effect of the Iraq war.

The poll, produced for ABC by Langer Research Associates, finds that the intensity of negative views of the war in Afghanistan has increased considerably. Nearly half now feel "strongly" that the war has not been worth it, more than three times the number who strongly feel it's been worthwhile - numerically the largest gap between the two in ABC/Post polls since early 2009.

Despite these negative impressions, most Americans don't want U.S. forces to leave Afghanistan entirely: 53 percent say they'd rather remove most troops but keep some in place there to train Afghan soldiers and for counterinsurgency, versus 43 percent who would prefer to see all U.S. troops withdrawn in the year ahead. The Obama administration was reported earlier this month to be keeping both options on the table.

Attitudes on withdrawal are closely related to views of the war's impact. Among people who think it's been worth fighting or has contributed to long-term U.S. security, roughly seven in 10 want to keep some troops in place. Among those who see the war more negatively, support for a continued role drops to just more than four in 10.

GROUPS - After nearly 12 years of fighting, dissatisfaction with the war in Afghanistan is broadly based, with majorities across demographic groups saying it hasn't been worth the costs, including, for example, 51 and 57 percent of Republicans and conservatives, respectively. That jumps to 77 percent among liberals, 74 percent of Democrats and 71 percent of independents.

Republicans are the only remaining group in which a clear majority, 55 percent, thinks the war has made the country more secure. Conservatives are essentially divided on the question, while majorities of Democrats, independents and liberals say the war has not aided U.S. security.

While most Americans opt for keeping some troops in Afghanistan beyond 2014, rather than a complete pullout, that question produces about an even split in some groups, including Democrats, independents, liberals and nonwhites.

METHODOLOGY - This ABC News/Washington Post poll was conducted by telephone July 18-21, 2013, in English and Spanish, among a random national sample of 1,002 adults, including landline and cell-phone-only respondents. Results have a margin of sampling error of 3.5 points, including design effect.

The survey was produced for ABC News by Langer Research Associates of New York, N.Y., with sampling, data collection and tabulation by Abt-SRBI of New York, N.Y.