(CNN) -- A man wearing an Afghan National Army uniform shot at coalition service members in eastern Afghanistan Friday, killing one, officials said.
NATO's International Security Assistance Force did not say which country the deceased soldier was from. But a local police chief in Kunar province said the deceased soldier was an American.
It is unclear whether the attacker is an Afghan soldier or an infiltrator wearing the uniform.
Police said the attacker was an Afghan soldier. But the Taliban said the attacker was part of the Taliban and had infiltrated in order to attack foreign soldiers, said Zabiullah Mujahid, a spokesman for the militant group.
The problem of Afghan troops who have turned their weapons on allied forces -- so-called green on blue attacks -- has intensified this year.
In March, Gen. John Allen, the commander of the NATO-led International Security Assistance Force, said "an erosion of trust that has emerged from this," but said that the systems the Afghans and ISAF have in place to help stop these attacks before they happen is having an effect.
Allen said ISAF officials are working on a new procedure to check the backgrounds of Afghans who sign up for the army or police force, and the Afghans "have taken a lot of steps themselves."
The attacker was able to escape after the shootings, police said.