The compliment from US ambassador to Afghanistan, Zalmay Khalilzad, was in sharp contrast to the collective dismay voiced by human rights groups over the appointment.
Afghan regional commanders have been accused of rights abuses and non-governmental groups have been demanding that they be sidelined.
"I believe that President Karzai's decision to give a role to General Dustum and give a role to other regional strongmen is a wise policy," Khalilzad said.
"I think that's part of the approach to minimise the use of force."
New York-based Human Rights Watch says Dustum has been implicated in countless human rights abuses in the last quarter of a century.
His forces were accused of letting hundreds of Taliban prisoners suffocate to death in transport containers after their capture in 2001, a charge the general has denied.
Dustum, who finished fourth in October's presidential elections, had served as a military adviser in Karzai's previous interim administration, but relations were often strained.
When Karzai came to power after the Taliban's overthrow by US-led forces in 2001, his attempts to stabilise Afghanistan were undermined by repeated clashes between Dustum's fighters and rival ethnic Tajiks.
Khalilzad said Washington had tried to persuade regional commanders to give up their heavy weapons and militias, especially since the election, which gave Karzai a clear mandate to build democratic institutions.
"You can always threaten people and say, 'You will do this in 24 hours or I am going to come and bomb you'," he said.
"We try to the maximum degree possible to avoid that... Keep the use of force in your background but talk to people about the wisdom of this new opportunity."