The attack occurred during a routine patrol in the eastern province of Parwan, a Taliban stronghold. The militants have been fighting to regain power since being overthrown by a US-led military coalition in 2001.
A suicide bomber killed three NATO soldiers and wounded at least three more during a patrol in eastern Afghanistan Sunday — the Taliban claimed responsibility for the attack.
A statement issued by the western alliance said: "Three Resolute Support service members were killed by a suicide bomber during a combined, dismounted patrol with Afghan forces in eastern Afghanistan."
'Strengthen our resolve'
US Army General John Nicholson, commander of NATO's Resolute Support operation and US Forces–Afghanistan, said the alliance members would not be deterred by the attack.
"Their sacrifice will endure in both our hearts and history and further strengthen our resolve," he said in a separate statement.
At least one American and two Afghan soldiers were injured in the attack. However, the nationalities of those killed were not immediately released, pending notification of their families.
The attack occurred at 6 a.m. local time (0130 GMT/UTC) in the Khalazai section of Charikar, the capital of Parwan province, 60 kilometers (35 miles) north of Kabul.
Taliban wants Islamic law
Wahida Shahkar, spokeswoman for the Parwan provincial governor, said the suicide bomber attacked foreign soldiers during a routine foot patrol.
The US military ended its primary operations in Afghanistan in 2014 but a 16,000-strong residual force remains for training and counterterrorism operations.
US Special Forces are frequently deployed in eastern Afghanistan, which continues to be one of the deadliest parts of the country for foreign forces.
The Taliban are fighting to restore strict Islamic law after being toppled in 2001 by US-led military forces. The militants issued a statement claiming responsibility for today's attack.
"We have killed eight US invaders in a tactic bombing," said Taliban spokesman Zabihullah Mujahid. "The invaders had to bring three helicopter ambulances to protect their forces."
One US soldier and an Afghan counterpart were killed during a combat operation in mid-July.
bik/kl (Reuters, AFP, dpa)