The US-led coalition in Afghanistan says it will investigate a recent attack to see if any of the casualties were caused by friendly fire.
Four Canadian troops were killed by friendly fire in 2002
One US and one Canadian soldier were killed after the coalition base in southern Helmand province came under attack last week.
A US soldier and three Canadian soldiers were also wounded during the attack by suspected Taleban militants.
Helmand province has been at the centre of a recent upsurge in fighting.
"The investigation will determine all the facts and circumstances surrounding the incident, including whether any of the casualties may have resulted from friendly fire," the statement issued by the US-led coalition in Kabul said.
"After reviewing initial reports of enemy contact, the Combined Forces Command... commander determined that an investigation was warranted."
The investigating team will be made up of Americans, Canadians and Afghans, the statement said, who will produce three separate reports.
The BBC's Alastair Leithead in Kabul says the fighting last week was the biggest battle in Afghanistan for two months. The US military says 32 militants were killed.
The Taleban were reported at the time as saying that they had begun a new spring offensive against foreign and government forces.
This will not be the first investigation into friendly fire since the US-led invasion of Afghanistan.
Four Canadian troops died in 2002 after being bombed by a US pilot in Kandahar province. He was subsequently fined $5,672 and reprimanded after being found guilty of wilful misconduct and dereliction of duty.
Former American football player turned soldier Pat Tillman was killed by friendly fire in 2004 when his patrol was hit by gunfire in Khost province.