By Phil Stewart
WASHINGTON (Reuters) - Afghanistan troop casualties climbed 79 percent during key fighting months this year as the still-resistant Taliban kept up the pace of its attacks and NATO forces moved into a support role in preparation to end their combat mission, the Pentagon said on Friday.
The data came in a Defense Department report to Congress that also showed NATO casualties falling 59 percent during the April-September period under review. The Pentagon did not provide the number of casualties for either year.
Despite the jump in Afghan casualties and high attrition rates in the Afghan army, the report was broadly upbeat about the Afghan National Security Forces, or ANSF. It said they had proven their ability to hold hard-won gains from the 12-year-old war, even as NATO forces pulled back from the front lines.
It also cautioned that Afghan forces would be at risk without continued international support after NATO wraps up its combat mission at the end of 2014.
"After 2014, ANSF sustainability will be at high risk without continued aid from the international community and continued coalition force assistance," the report said.
"With assistance, however, the ANSF will remain on a path towards an enduring ability to overmatch the Taliban."
The report's release came ahead of the assembly later this month of Afghan tribal elders, who are due to weigh a bilateral security pact with the United States, including a contentious provision giving immunity to U.S. forces.
Without the pact, Washington has threatened a complete pullout of its forces after 2014 - the so-called zero option. The United States now has about 48,500 troops in Afghanistan, a figure set to fall to 34,000 by early next year.
The report said the Taliban insurgency kept the same tempo of operations during the April-September period as seen in the past three years, maintaining influence in rural areas "that serve as platforms to attack urban areas."
It had also consolidated gains in some of the rural areas where it traditionally held power.
Although NATO estimates the number of al Qaeda fighters in Afghanistan to be "very low," the report also said that dozens of al Qaeda operatives and facilitators were killed during counter-terrorism operations during the six month period.
The Pentagon said Taliban sanctuaries across the border in Pakistan were "a major factor preventing their decisive defeat in the near term."
(Reporting by Phil Stewart)