WASHINGTON - Citing limited gains, a US Defense Department report on Tuesday painted a mixed picture of the war in Afghanistan, with an insurgency that's capable of withstanding losses and launching high-profile attacks even as it faces mounting pressure from US forces.

The report, mandated by Congress, said the Taliban has been unable to reclaim territory taken by foreign and Afghan forces in Kandahar and Helmand provinces, as the Afghan security forces makes significant improvement during the past months.

The report, which covers the situation of the past six months, said that attacks on US and Afghan forces declined in 2011 for the first time in five years and that the positive trend appeared to be continuing into 2012.

However, the report said Taliban remains "resilient and determined," and will attempt to regain lost ground and influence in the coming months.

It noted the insurgents still have safe havens in Pakistan, posing biggest threat to the long-term success of the war.

It also asked the question if the Afghans could hold on to the security gains made in the past years following a withdrawal of forces in the coming years. Foreign troops will be out of Afghanistan by the end of 2014.