A growing Islamic insurgency in the south and east and renegade factional militia based in the north and west are threatening security in Afghanistan less than four months before landmark elections are due to be held.
Four US soldiers from a special operations unit were killed in action yesterday in one of the worst combat losses suffered by the 20,000-strong American-led force since it helped defeat the Taliban in late 2001.
The US military has not said who was to blame for the deaths, but they took place in the southern province of Zabul where remnants of the ousted Taliban opposed to foreign and Afghan forces have been active in recent months.
On the same day, in the southern province of Helmand, seven government soldiers were killed along with four Taliban guerrillas in a series of coordinated raids on official targets.
Also this week, US warplanes were called in to pound militant positions in the southern province of Kandahar, and two US soldiers were wounded in skirmishes with guerrillas near the Pakistani border in the east.
A Norwegian peacekeeper was killed a week ago in Kabul in the first fatal attack using rocket-propelled grenades on the force.
"The threats to security continue," UN spokesman Manoel de Almeida e Silva told reporters on today.
"They continue because...of what we call the 'spoilers', those who oppose this process, those who do not want to see a new Afghanistan that meets the expectations and the aspirations of the vast majority of this people."