One US soldier and two government soldiers have been killed in separate incidents in south-eastern Afghanistan, it has emerged.
The US soldier died when troops came under attack on Wednesday evening in the south-east of the country.
The Afghan soldiers were reportedly ambushed by Taleban fighters close to a US military base.
The US has been leading a number of military operations in recent months against the Taleban.
Earlier this week, the Taleban leader, Mullah Mohammed Omar was reported to have organised a new war council to fight the US-led forces.
"One Special Operations member was killed and two were wounded in the vicinity of Gardez, Wednesday," Colonel Douglas Lefforge told reporters at the US Bagram air base on Friday.
Mullah Omar is said to have reorganised resistance to the US
He gave no details of who the attackers may have been.
Gardez lies 100 kilometres (62 miles) south of the capital Kabul.
An Afghan official was more forthcoming when he spoke to Reuters news agency about the deaths of two Afghan soldiers.
Afghan troops "came under heavy attack" on Wednesday close to the town of Spin Boldak on the border with Pakistan, the unnamed official said.
"The Taleban used rockets and heavy machine guns and killed two Afghan soldiers on the spot. The Taleban are again regrouping in eastern and southern Afghanistan," the official said.
The US has insisted it will not pull out of Afghanistan while the Taleban is still a threat.
"The United States will withdraw forces once we are sure that the government of Afghanistan feels perfectly secure and the people of Afghanistan have found necessary stability," visiting Deputy Secretary of State, Richard Armitage, said last month.