WASHINGTON: Despite their growing effectiveness, Afghan forces will need support from the United States and its allies even after the Nato combat mission ends next year, according to a new Pentagon report that implicitly warns against a “zero-option” of total withdrawal.

US officials have said the United States could potentially pull out all of its troops from Afghanistan next year, amid tensions between President Barack Obama's administration and the government of Afghan President Hamid Karzai.

The Defence Department's twice-yearly report to Congress on the Afghan war effort suggested that preserving hard-won gains after nearly 12 years of war could depend, at least in part, on the size of whatever force the United States and Nato leave behind after 2014.

The United States has been talking with officials in Afghanistan about keeping a small residual force there of perhaps 8,000 troops, while Nato allies contribute thousands more.

“Assessing whether the gains to date will be sustainable will be difficult to do until the exact size and structure of the post-2014 US and Nato presence is determined,” according to the report, titled “Progress Toward Security and Stability in Afghanistan.”

The report said the Taliban lost territorial control in 2012 and through the first quarter of 2013 and was “now less capable, less popular and less of an existential threat to the Afghan government than in 2011.”

Still, it cautioned that the Taliban remained resilient, benefiting from corruption within the Afghan state that alienates the population and from sanctuaries in neighbouring Pakistan.

“Pakistan continues to adopt a posture of acceptance, and occasional support, to Afghan-focused insurgent groups that attack US and coalition forces,” the report said, renewing longstanding accusations that Islamabad rejects.—Reuters