Rasmussen was speaking at a joint news conference with Pakistani Foreign Minister Shah Mehmood Qureshi. The NATO chief was in Pakistan to discuss regional security a day after an international conference in Afghanistan.

"We appreciate very much what Pakistan has done to promote regional stability and security," Rasmussen said. "I would like to commend the Pakistani government and the Pakistan military for your operations in the tribal belt with the aim to improve the overall security situation."

Rasmussen, on his first visit to Pakistan, also expressed support to the government of President Hamid Karzai and said NATO would not leave Afghanistan "prematurely."

An international conference in Kabul on Tuesday set an ambitious deadline for the Afghan forces to lead security across the country by 2014, and said the Afghan government would be given more responsibility for its own affairs.

Rasmussen described the conference as a success that would lead to an Afghan-led process and said the goal was to hand over responsibility to Afghans themselves, when conditions permit.

"We are there to assist the Afghan government ... to secure their own country, but we are also there to ensure overall stability in the region," he told reporters after his meeting with Qureshi.

"So a gradual transition ... will not be driven by the calendar, it will be driven by conditions," said Rasmussen, who attended the Kabul conference.

Violence is at its worst in Afghanistan since US-backed Afghan forces overthrew the Taleban in late 2001 for refusing to give up Al-Qaeda members following the Sept. 11 attacks in the United States.

The United States, which leads the NATO forces in Afghanistan, plans to start withdrawing troop in July 2011, and the British Prime Minister David Cameron said on Wednesday his country's troops could start withdrawing as early as next year.

Rasmussen said Afghan soldiers would be trained and educated to take responsibility themselves, but cautioned that leaving Afghanistan prematurely would allow Taleban insurgents to return.

"If we were to leave Afghanistan before we have finished our job then the Taleban will just return to Afghanistan and create again a safe haven for international terrorism. Afghanistan could once again serve as a launch pad for terrorism attacks."