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The American mission to bring order to this unruly country is being handed to a multinational force led by the NATO alliance, a move that will subordinate U.S. troops under foreign command in a combat situation for the first time since World War II.

NATO's ambitious mission could inject the flagging European-North American alliance with a sense of purpose and also might take the heat off Washington, seen in this region as too eager to fight Muslims. But there are questions whether NATO will engage in the type of offensive operations the U.S.-led coalition has.

"NATO needs to grab hold of this mission for NATO's sake," U.S. Central Command chief Gen. John Abizaid said in a recent interview with The Associated Press. Jumping outside European boundaries is "where the alliance needs to go to stay relevant for the future."

Abizaid and others have said the Afghanistan mission marks a historic expansion for NATO that could see the alliance taking further missions in Africa or elsewhere. Even after the takeover, however, the U.S. is expected to maintain a separate counterinsurgency force in Afghanistan to hunt Taliban and Al Qaeda holdouts.

British Army Lt. Gen. David Richards is to take command in Afghanistan this summer, the first time U.S. ground troops at war would be placed under foreign leadership in more than 50 years.

"That's a first — since World War II," U.S. Brig. Gen. Douglas Raaberg told the AP on Sunday.

Americans won't be far from the top, however. Richards' deputy will be Maj. Gen. Benjamin Freakley, now commander of the U.S. Army's 10th Mountain Division.

"It has always been a contentious issue. Americans don't like to be under command of other nations," said Amyas Godfrey, a military analyst with the Royal United Services Institute for Defense and Security Studies in London.

But in this case, he added: "I don't think it'll be a problem. Brits and Americans have been working hand in hand for over three years."

U.S. troops have been under foreign command before — in a U.N. force in Macedonia in the 1990s and under NATO in Kosovo, where they continue to serve since 1999. But both missions were peacekeeping operations after hostilities had largely ended. U.S. troops haven't been under foreign command in a theater where fighting continues — like Afghanistan — since serving with British Field Marshall Bernard Law Montgomery in some campaigns of World War II.

Some 5,000 to 6,000 Americans will join the NATO force in Afghanistan, which will more than double in size by November, from its current 10,000 troops to around 21,000 troops.

NATO is already moving into Afghanistan's rebellious southern provinces with 6,000 troops, mainly from Britain, Canada and the Netherlands. That deployment is expected to be completed in the summer and will quickly be followed by the alliance moving into the east, considered Afghanistan's most dangerous sector.

"NATO is going from the north and west that were relatively quiet to areas where there's going to be challenges," Abizaid told the AP. "Tackling these things is going to be important for the alliance."

Yet questions remain over the NATO forces' mandate as they start moving into the south amid rising militant attacks and suicide bombings.

One Western diplomat based in Islamabad said it remains unclear whether NATO will be willing to take and inflict casualties. NATO's limits are likely to be quickly tested by militants, the diplomat said, speaking on condition of anonymity because he is not authorized to speak to journalists on the record.

Defense Secretary Donald H. Rumsfeld has said the 19,000 U.S. troops in Afghanistan will be reduced to about 16,000 by the summer. About 5,000 to 6,000 of them will go under the NATO command, aimed at maintaining stability and security. The rest will be in the separate U.S. counterinsurgency force to hunt Taliban and Al Qaeda holdouts, which will remain under U.S. military command, in close liaison with NATO.

U.S. B-52 bombers and A-10 ground-attack jets will remain in Afghanistan to back up both NATO and the separate U.S. force, said Raaberg, Centcom's deputy chief of operations.

Whether U.S. military control of Afghanistan's airspace gets transferred to NATO has yet to be decided, he said.

Not all NATO forces will be as "robustly engaged" as others, Abizaid said. Some are restricted by national rules, or caveats, from engaging in combat, crowd control and other confrontations.

"There will be a whole range of national capabilities displayed here and willingness to engage in tasks," Abizaid said. "We look to minimize as many of those caveats as possible."

In contrast to Afghanistan, NATO has refused to take a large role in Iraq, agreeing only to handle limited training of Iraqi troops in a U.S.-led war unpopular in most NATO countries. U.S. intervention in Afghanistan is viewed as a more justified conflict.

Godfrey, a former British intelligence officer in Iraq, said the "internationalization" of the Afghan counterinsurgency duties takes the heat off Washington's stretched troops and battered image.

"America needs NATO in this situation," Godfrey said. "It will take pressure off America and the idea that America is perpetuating a war against Muslim nations, and that it's always America on the front lines."

Major contributors to the NATO forces include more than 3,000 British troops, more than 2,000 Canadians, as well as around 1,000 Italians, Germans, French, Spanish, Dutch and others. Non-NATO members include Australia, New Zealand and Albania.