NATO took over command of insurgency-wracked southern Afghanistan from the United States on Monday, and the new commanding general warned he will "strike ruthlessly" when required against Taliban rebels.

The changeover, marked by a simple flag ceremony at Kandahar air field, came after dozens of Taliban died in the latest fighting, and a car bomb intended for the governor of an eastern province killed eight people, including five police.

NATO's mission is considered the most dangerous and challenging in the Western alliance's 57-year history. It coincides with the deadliest upsurge in fighting in Afghanistan since late 2001 that has killed more than 800 people — mostly militants — since May.

The leader of U.S.-led coalition forces, Lt. Gen. Karl Eikenberry, transferred command to the chief of the NATO-led force, British Lt. Gen. David Richards, at the ceremony held inside a big white marquee, broiling under the fierce midday sun, amid the roar of planes and helicopters taking off from what is the main military base for operations in southern Afghanistan.

The coalition, first deployed nearly five years ago to unseat the Taliban regime for harboring Usama bin Laden, now is focusing its attention on eastern Afghanistan, where Al Qaeda and Taliban are also still active.

"The war on terrorism began here in Afghanistan and it continues today. We must never forget that," Eikenberry said. "The United States will not leave Afghanistan until the Afghan people tell us the job is done."

Soldiers carried out a flag staff with the coalition's ensign and replaced it with that of NATO's International Security Assistance Force, which first deployed to Afghanistan in August 2003, and has gradually expanded its presence across the country, from Kabul, to the north and then west.

The more volatile south — the region where the hardline Taliban militia was born and has staged its bloody resurgence this year — represents a much stiffer challenge. About 8,000 mainly British, Canadian and Dutch forces have deployed there, bringing the NATO force's nationwide presence to nearly 18,000. A similar number of U.S.-led coalition forces will remain in Afghanistan.

Richards said the expansion showed the "complete commitment of NATO and its partners in ISAF in ensuring that Afghanistan and the Afghan people are allowed to flourish in a peaceful, prosperous, Islamic democracy."

But it represents a huge test for NATO, which was founded in 1949 as a deterrent against the Soviet bloc. Since the end of the Cold War, the alliance has conducted aerial combat operations during the wars in Bosnia and Kosovo in the 1990s, but the Afghan mission will be its first major ground combat operation.

Richards indicated that the NATO force — also including the first U.S. forces to be commanded by a non-American — would continue using the heavy fire power that has been employed by the coalition in recent months, in response to the escalation in militant attacks, including mass assaults on several small southern towns.

"We will retain the capability and will to strike ruthlessly at the enemies of Afghanistan when required," the British general said.

NATO nevertheless hopes to bring a new strategy to dealing with the Taliban rebellion: establishing bases rather than chasing militants. It is also wants to win the support of locals by creating secure zones where development can take place.

Given the level of violence, questions remain whether it can achieve the stability required to let aid workers work in a lawless and impoverished region, where about a quarter of Afghanistan's huge opium crop is grown.

The takeover in the south follows three days of intense fighting that left nearly 60 suspected Taliban and eight others dead.

A bomb planted in a car exploded near a mosque Monday in Farmay Adha, near the eastern city of Jalalabad, killing eight, including five police and three children, officials said. Sixteen others were wounded.

Thousands of mourners had gathered in and around the mosque to mark the death of Younis Khalis, a former mujahedeen commander and Islamic hard-liner, who died July 19.

Provincial police chief Gen. Abdul Basir Solangi blamed the Taliban for the bombing, which he believed was aimed at Nangarhar Gov. Gul Agha Sherzai, who drove away from the mosque minutes before the explosion.

Sherzai escaped a May 3 assassination attempt when a bomb planted in a jeep exploded outside his office.

In southern fighting, some 200 Afghan forces killed 23 Taliban insurgents Sunday in raids on two hide-outs near the Helmand provincial town of Garmser, which Taliban forces overran and briefly took control of earlier this month, police said.

Another 10 insurgents were killed Sunday while fighting Afghan troops in clashes in southeastern Paktika province, and four were detained. Four militants died in separate explosions while planting bombs in southern Kandahar province. And on Monday, two more Taliban were killed in a clash with police in southern Zabul province.

Coalition and Afghan troops killed 20 militants on Saturday in southern Uruzgan province, where some 1,500 Dutch troops have deployed.

More than 800 people, mostly militants, have been killed in Afghanistan since May, according to an Associated Press tally of coalition and Afghan figures.

Coalition operational commander U.S. Maj. Gen. Benjamin Freakley said at Monday's ceremony that 50 coalition soldiers have died since February.

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