General David Petraeus has called for unity to tackle the conflict in Afghanistan
General Petraeus arrived in Kabul on Saturday to take command of American and NATO forces in the country. After touching down, he flew by helicopter to the headquarters of the International Security Assistance Force.
On the same day, NATO forces accidentally killed two civilians, including a woman, and wounded another during an operation against Taliban militants in the south of the country.
NATO says it happened as the soldiers searched compounds for a Taliban commander.
The troops later found and detained the Taliban commander being sought in the operation, which also resulted in the killing of an insurgent and the wounding of another.
Addressing about 1,700 guests at the US embassy in Kabul Gen Petraeus called for civilian officials and the military to make a "united effort" to tackle the nation's nine-year conflict.
The general said that military-civilian cooperation was "not optional".
"This is an effort in which we must achieve unity of effort and common purpose. Civilian and military, Afghan and international, we are part of one team with one mission," he said.
The BBC reports that Gen Petraeus is to meet Afghan President Hamid Karzai later on Saturday.
The military leader faces a number of tough challenges over the coming months, including reducing casualties. June saw the highest number of deaths among Nato personnel in the nine years of war - 102.
General Petraeus is taking over from General Stanley McChyrstal, who was sacked last month for ridiculing members of the Obama administration in an interview with Rolling Stone magazine.