With snow past their ankles and their view of forbidding mountains blocked by low-slung cloud, U.S. soldiers in Afghanistan's restive east are taking advantage of a bitter winter to brace for fresh fighting in spring.
The extreme cold has forced a lull in fighting at rugged outpost Zerok in Paktika province, located 20 km (12 miles) from the porous, unruly border with Pakistan, which teems with insurgents linked to the Taliban and al Qaeda.
Afghanistan's east has emerged as the new focus of attention as worries mount over a narrow strip of land that the United States has dubbed the most dangerous place in the world.
NATO-led forces are currently in the process of handing over control of security to the Afghans ahead of a planned exodus of foreign combat troops to be completed by the end of 2014.
But officials in the U.S. military and Afghan government are increasingly concerned by the challenge of securing the 2,640 km border that many frontline soldiers believe is too rugged to hold. Failing to do so would allow more militants to cross over, complicating peace efforts in Afghanistan.
Ringed by mountains dotted with evergreen trees, Zerok is one of a series of remote outposts that form the first line of defence against insurgents crossing the border into Afghanistan to launch attacks, according to U.S. and Afghan officials.
It is that first layer where the insurgents are met by a security element that stops their flow, said Captain Craig Halstead, commander of the U.S. Army's Bravo Company, 2nd Battalion, 28th Infantry Regiment at Zerok.
By training the Afghan army and police, who have been patrolling the frozen peaks alongside his own troops, he hopes that when fighting renews with the March thaw, the Afghans will have absorbed enough for insurgents to find a tougher, more disciplined opponent.
But U.S. officers are wary of the hurdles still ahead.
What the (Afghan army is) not very good at is logistics, planning at levels higher than company (30-60 men), said Major Joseph Buccino, a spokesman for the U.S. forces in Paktika, where around 3,400 American soldiers are currently serving. This will drop to just over 3,000 before the summer fighting season.
American soldiers at Zerok said their Afghan partners have only recently started taking the initiative when planning operations, and handing orders down to soldiers on the ground is still relatively new for them.
Drug use, hastily trained ranks and widespread corruption are hindering the Afghan police and army nationally, some Afghan and U.S. officials say.
Halstead, who has been at Zerok since July, said another major difficulty is the support local Afghans give to the insurgency, often through fear of militant reprisals.
The people sometimes don't have a choice, because of intimidation, threats, and the coercive tactics insurgents can use against them, he said.
SERIOUS CROSS-BORDER THREATS
Underscoring Afghan government concerns about the challenges, no whole provinces bordering Pakistan were chosen for the first phase of transition to Afghan security, completed last July.
Three districts in Paktika, two of which touch the border, were handed over to Afghan control in November, while for the second tranche, four areas in eastern Nangarhar province were selected, but none are actually on the border.
We have some serious cross-border threats. We keep pushing Kabul to deal with this effectively, Nangarhar deputy governor Mohammad Hanif Gardiwal told visiting reporters, saying security forces lacked heavy weapons to counter the insurgents.
Currently, around 30,000 foreign troops are serving in the 14 provinces making up Regional Command East, around a quarter of the total in the country.
There will be an awful lot of pressure to be very aggressive (this summer), said Buccino, adding it will be the last time the coalition will have extra soldiers sent into the area as part of a two-year surge that began in 2010.
While numbers for 2013 are not yet known, they are certain to fall. U.S. President Barack Obama last June announced a rapid drawdown of American forces from a peak of 101,000 to around 67,000 by the end of the 2012 summer, in a high-risk strategy underpinned by the ability of the Afghan forces left behind.
Further north, not far from the Pakistan border in Jalalabad, the capital of Nangarhar province, local officials and ordinary Afghans bemoaned what they said is their country's inability to secure the rugged border districts.
Security here in the city is good but they won't be able to protect the remote areas further east, said shopkeeper Houmayin in the city from where U.S. commandos launched the raid that killed Osama bin Laden in Pakistan.
They are Taliban land, Houmayin said, perched upon mounds of nuts and chocolates in his shop overlooking a busy road lined with palm trees.
Jalalabad city, along with four other districts, will be officially handed over to Afghan security forces by the end of this week.
Mufti Moinshah Haqqani, a member of the provincial government, said the border was a hotbed of expert bomb-making activity, with financing from within the Pakistani government, a claim commonly made by Afghan officials.
Pakistan denies allegations it supports militant groups.
No matter how much we equip our police and our army, or how much investment we put in, there is no way security will be improved in the Pakistani border districts, he said alongside other members of the Nangarhar provincial council.
Unless the Pakistani government succumbs to pressure to stop interfering in Afghan affairs, transition in those areas will stay a challenge.
(Editing by Rob Taylor and Jonathan Thatcher)