COMBAT OUTPOST MONTI, Afghanistan: Perched high in a twisting Hindu Kush valley with distant views of Pakistan, Combat Outpost Monti is an idyllic spot. But it is also one of Afghanistan's most dangerous corners and frequently peppered with mortars.

The remote US base with sweeping mountain views in the northeastern province of Kunar is on the frontline of the fight to stop insurgents allegedly crossing from Pakistan, 13 kilometres away, to launch attacks in Afghanistan.

The US embassy in Kabul was last week victim of one strike which Washington blamed on the Haqqani network. Both the secretaries of defence and state demanded Islamabad act against the Taliban-allied militant group which the US believes is based in Pakistan.

But with so-called limited cooperation from Pakistan, US troops on the frontier face a race against time to make real progress before the last foreign combat forces leave Afghanistan in 2014 and hand control to Afghan troops.

Major Chris Rankin, a senior intelligence officer in the Kunar area, said the Pakistani side was failing to hold up its end.

US-Pakistani meetings on cross-border issues locally “really just don't occur because there's really either no interest...or no desire to do that at the tactical level”, he said.

“We've extended the olive branch here...we have at least showed our interest in conducting these meetings and this has not been reciprocated.”

Another senior US military official spoke of how some Pakistani officials' “noses are out of joint” after May's killing of Al-Qaeda leader Osama bin Laden by US commandos in Pakistan.

US operations in Pakistan are normally limited to drone strikes and bin Laden's killing on Pakistani soil without the government's foreknowledge chilled relations between Washington and Islamabad.

Pakistan and Afghanistan have for years traded accusations over the militant groups embedded in both countries, who criss-cross the porous, unmarked border and fight security forces from both governments.

Pakistan blames any cross-border incursions into its neighbour's territory on the Afghan Taliban, while its military says it has deployed nearly 147,000 troops to the northwest and lost 3,000 of them in fighting since 2001.

But the troops at COP Monti say a lack of cooperation means frequent attacks on their base which have injured dozens of troops and are increasing in scale.

“Before, it was every other day, one or two mortars a day,” said Sergeant John Henington. “Now it's two or three times a week but they're dropping 11 or 12 mortars on us in about 10 minutes.”

The troops usually respond with two giant artillery pieces but steer clear of scaling the mountains to hunt down their foes, partly because of the perilous geography.

“Chasing the enemy is the biggest mistake you can do, they're like ghosts,” said Captain Michael Kolton, the 29-year-old in charge at COP Monti.

“You'll kill the dumb ones but the smart ones will never get caught that way. You'll spend all your resources on 10 dudes running around the mountains.”

But with a policy of focusing on population centres instead of rural areas, troops are also backing off counter-insurgency operations in Kunar and neighbouring Nuristan, engaging elders and training up Afghan forces instead.

“I think that's a giant distraction,” Kolton said of pursuing insurgents.

“I think that the people will kick them out.”

The United States no longer has any permanent presence in Nuristan although denies this is because of security concerns, and disputes claims from some analysts that this could allow insurgents to build safe havens.

“If you try to be strong everywhere, you can't be strong anywhere,” said Lieutenant Colonel Chad Carroll, public affairs director for Nato-led operations in eastern Afghanistan.

“We have focused on those key areas that we have deemed important to our tactical mission.”

He also stressed that Nato forces still take part in periodic sweeps for insurgents such as one with Afghan commandos in Nuristan last week which officials said killed 70 insurgents.

Carroll insisted that it was possible for foreign troops to accomplish their mission in the region, a key part of which is cracking down on cross-border strikes, before 2014.

But others seem less sure, doubting the wisdom of the United States and other nations announcing their intended withdrawal date so far in advance and questioning Pakistan's willingness to cooperate.

“It's less about relations between the US and Pakistan (than) Pakistan putting in enough resources to secure the border,” said an international security officer in Kunar speaking anonymously.

“Pakistan is kind of a mess right now in a big way. So much of their focus remains on India rather than Afghanistan.”