NATO's top military commander voiced concern on Monday about the porous Afghan-Pakistan border, which can be used by insurgents involved in deadly fighting with alliance troops in southern Afghanistan.
But, speaking at the opening of a new intelligence-gathering centre for the North Atlantic Treaty Organisation, General James Jones declined to criticise the Pakistani government over its management of border security.
"It's clear that the border is not a sealed border," he said, when asked if Pakistan's behaviour was leading indirectly to the deaths of NATO soldiers in Afghanistan.
But he said: "I quite understand the concerns of our troops on the ground... and we are going to be working on this problem assiduously in the weeks and months ahead."
NATO assumed command of foreign forces throughout Afghanistan this month, taking charge of the east of the country from the US-led coalition that toppled the Taliban regime five years ago.
The Taliban insurgency has worsened dramatically in recent months, with insurgents killing scores of foreign and Afghan troops in mass attacks and also intensifying a vicious campaign of suicide and roadside bombings.
Militants are widely believed to move across the porous and rugged border with Pakistan.
But Pakistan says the 80,000 troops it has along the frontier prevent any major incursions.
The NATO general played down concerns about the need for more troops, saying NATO member states had responded to recent appeals, including Poland, Canada, Romania and Norway
"I believe there are other nations which will when they are ready make similar announcements," he said.
"Bit by bit we are getting up to the totals that we need and I'm quite content with the pace. We still need a little bit more mobility, a litle bit more maneuvrability.
Jones was speaking at the opening of the Intelligence Fusion Centre at an air base in Molesworth, north of London.
The IFC aims to speed up the collection and distribution of military intelligence for NATO operations.