The U.S. military in Afghanistan has confirmed four American soldiers were killed in a roadside bombing in eastern Kunar province.
A military statement says the U.S. troops' armored vehicle was hit by an improvised explosive device while on patrol Sunday.
Also Sunday, a former Afghan president escaped unharmed after a suicide bombing in Kabul. He accused Pakistan's secret service of being behind the attack.
Sibghatullah Mujaddedi, who chairs the upper house of Afghanistan's parliament, says Pakistan's Inter-Services Intelligence agency organized the bombing that killed four people -- two attackers and two bystanders.
He did not offer any proof, and Pakistani officials denied the allegation.
Afghan President Hamid Karzai said the attack will be investigated before blame is placed on anyone.
An Interior Ministry spokesman Yousuf Stanizai said no one has claimed responsibility for the assassination attempt carried out by two men in a car.
Tension has been high between Pakistan and Afghanistan as Pakistan disputes Afghan intelligence information that says Taleban and al-Qaida terrorists are moving freely in Pakistan.