NATO forces have been tightening security in Kandahar. The operation to assert control over the Taliban stronghold will continue to accelerate in the coming months.

Afghan President Hamid Karzai has urged tribal leaders to support the campaign. He travelled to Kandahar on Sunday, where he gave a speech to tribal chiefs and religious leaders, calling for their help.

U.S. and NATO commander Gen. Stanley McChrystal was also there.

"This wasn't just a speech of a president, it was the personal call of a leader," McChrystal said. "Asking for partnership to help protect each other, each fellow Afghan. He said this would not be easy, it would take work, it would take sacrifice and it would take time. But I believe that the response he got from the people was reflective of their unity with him."

Many Kandahar residents have been worried the operation will lead to more civilian casualties.

So far this month, at least 39 international troops have been killed in Afghanistan, 27 of them were Americans.