The Taliban would "take revenge from the invaders and the savage murderers for every single martyr", they said in a statement on their website.
The US soldier walked off his base and broke into the homes of villagers in Kandahar province's Panjwayi district before dawn yesterday, killing 16 people, including women and
A soldier has been detained and the United States has offered condolences to the families and pledged that action will be taken against anyone found guilty of the massacre.
Kandahar is considered the birthplace of the Taliban.
"A large number from amongst the victims are innocent children, women and the elderly, martyred by the American barbarians who mercilessly robbed them of their precious lives
and drenched their hands with their innocent blood," the Taliban said.
"The American 'terrorists' want to come up with an excuse for the perpetrator of this inhumane crime by claiming that this immoral culprit was mentally ill.
"If the perpetrators of this massacre were in fact mentally ill then this testifies to yet another moral transgression by the American military because they are arming lunatics in Afghanistan who turn their weapons against the defenceless Afghans without giving a second thought."