A resolution approved unanimously by the 15-nation council on Monday expanded the scope of the International Security Assistance Force (ISAF) mission so it could provide security across the central Asian nation.
It is a change long sought by the UN and Afghan President Hamid Karzai who was called the Mayor of Kabul by critics who said he had no control outside of the capital.
But the resolution is likely to have little immediate impact as few countries say they are willing to commit the needed troops at this time.
Renewal of mandate
The resolution also would renew the force's UN mandate for an additional year.
"This resolution helps pave the way for the increased security in Afghanistan on which everything else is dependent," said US Ambassador John Negroponte, the Security Council president for October.
The first new troops in rural Afghanistan are expected to come from Germany, which has said it wants to send up to 450 soldiers to the northern district of Kunduz to form a Provincial Reconstruction Team, a group of aid workers under military protection.
Germany agreed to do so only if its soldiers were a part of the NATO mission and not the US force in Afghanistan of some 12,500 soldiers that is trying to track down al-Qaida and Taliban members in the south.
"This resolution helps pave the way for the increased security in Afghanistan on which everything else is dependent"
US Ambassador to UN
The US forces are those that remain in the country nearly two years after the United States invaded Afghanistan to topple its Taliban rulers after the September 11 attacks.
Washington blamed Usama bin Ladin and his al-Qaida network for the attacks and accused the Taliban of providing them with a safe haven.
But the Taliban has stepped up its military activity in recent months. More than 300 people, including aid workers, US soldiers and many Taliban fighters, have been killed in violence across the country since early August.
This includes 11 children wiped out in a US air strike in the village of Bermil, Paktika. The parents of the dead received an apology and less than one thousand dollars for each child from US military.
Relief groups and UN staffers, in particular, have also raised alarms over what they see as a trend of rising armed attacks on humanitarian workers in the Afghan provinces, which are largely under the control of a patchwork of feuding warlords.
Council members initially hesitant to send the multinational peacekeeping force into the provinces have now changed their minds, in hopes improved security would help Karzai's shaky Afghan Transitional Administration expand its authority across the country.