KUNDUZ, Afghanistan » Far from the heartland of the Taliban insurgency in the south, this once peaceful northern province was one place American and Afghan officials thought they did not have to worry about.

Afghan officials cut the police force here by a third two years ago and again earlier this year. Security was left to a few thousand German peacekeepers. Only one Afghan logistics battalion was stationed here.

But over the last two years the Taliban have steadily staged a resurgence in Kunduz, where they now threaten a vital NATO supply line and employ more sophisticated tactics. In November, residents listened to air raids by NATO forces for five consecutive nights, the first heavy fighting since the Taliban were overthrown eight years ago.

The turnabout vividly demonstrates how security has broken down even in unexpected parts of Afghanistan. It also points to the hard choices facing American, NATO and Afghan officials even if President Barack Obama decides to send more soldiers to Afghanistan, as he is expected to announce next week.

Even under the most generous deployments now under consideration, relatively few additional troops are expected in the north; most will be directed to the heartland of the Taliban resistance in the south and east.

Afghan and international officials say security never had to deteriorate so badly here. The Taliban were a scattered and defeated force in northern Afghanistan, long home to the strongest anti-Taliban resistance, the Northern Alliance.

But the government, and American military trainers, failed to remain vigilant to signs of Taliban encroachment, and reduced deployments in the northern provinces in order to bolster other, more volatile regions.

The decisions created vulnerabilities as Kunduz became a target with the opening of a new logistics route here for NATO supplies from Russia and Central Asia, over an American-financed bridge that opened in 2007. The route is supposed to serve as a strategic alternative to the treacherous passage through Pakistan, which is regularly attacked by Taliban militants.

Now, the Taliban have re-emerged with such force that during the presidential election in August, police officers were fending off attacks on the outskirts of the city of Kunduz, and militants were poised to overrun the center, officials said.

“;The Taliban were at the door of the city; the people thought the government was at an end,”; said a senior security official, who asked not to be named because of the nature of his work.

Since then, the threat has been somewhat contained after an operation by NATO and Afghan forces, but the province remains at risk.

Residents of Kunduz said they noticed that the Taliban reappeared in numbers in the region in the spring of last year.

At just that time, under pressure from the American military in charge of training the Afghan security forces, the government of President Hamid Karzai reduced the number of police officers in Kunduz to just 1,000 from 1,500, officials said. Then, earlier this year, the Interior Ministry ordered 200 police officers from every northern province to help secure the capital, Kabul, which was suffering increasingly serious attacks from insurgents.

A district like Khanabad, with a population of 350,000, has just 80 police officers now, the governor of Kunduz, Muhammad Omar, said in an interview. In the district of Chahardara, where hundreds of insurgents are at large, there are only 56 police officers, enough only to guard the district center and the main road.

“;It deteriorated suddenly,”; the governor said. “;The first reason is that we have very few police in Kunduz considering the strategic position of our region, and our police are not able to cover the whole region.”;

In fact, after their defeat in 2001, the Taliban never left the region. The insurgents laid low, but remained a menace to be constantly watched, according to the former governor of Kunduz, Gen. Muhammad Daoud, now a deputy interior minister.

The Taliban, who are mostly Pashtun, draw natural support through tribal ties with Pashtuns, who make up nearly half of Kunduz's population. Many of the fighters are local men who fled to Pakistan after 2001 and have returned in the last two years.

Central Asian fighters from the Qaida-linked Islamic Movement of Uzbekistan who also took refuge in Pakistan have reappeared, Afghan security officials said. Local journalists have seen some of them. The officials, who have captured some of the insurgents, accuse Pakistan's intelligence agency, al-Qaida and even Iran of supporting the resurgence. Pakistan and Iran routinely deny supporting the insurgency.

Whether it is the influence of foreign fighters, or the growing capability of the Taliban and another regional militant group, Hezb-e-Islami, Western officials say the insurgency in Kunduz has grown more sophisticated, mounting coordinated suicide car bombings and ambushes.

“;Clearly, this year we have seen much better fighters, capable of complex attacks,”; said one Western official.

Kunduz, a fertile farming region interspersed with desert, has had a trajectory similar to that of many other provinces, as the insurgents extended their hold through calculated intimidation and exploitation of tribal ties.

By the spring of 2008, militants started appearing in groups of as many as 100, with some foreign fighters among them, local residents and officials said.

They assassinated local leaders, including a Pashtun Quran reader who was beheaded, and quickly took control of several Pashtun areas, forcing ethnic Uzbeks from their homes in some districts, said Wakil Qara Qushlik, a local leader who had to flee his village last year.

The Taliban were at first more subtle with their fellow Pashtuns. A group of them came last spring without guns to introduce themselves to one prominent Pashtun family in Chahardara, and asked for support. They were worried about their own safety then, one family member said, asking not to be named. “;They were behaving very well with the people,”; he said. “;They stopped thieves, and brought law and order to the area.”;

But as elsewhere, that changed as the Taliban gained power and confidence, he said. This year the Taliban arrived with “;lots of cash, new dollars and guns,”; and began collecting ushr, an Islamic tax, from farmers.

Now, he said, they come to his home and demand to be fed, and have begun an intimidation campaign against his family for not supporting them at the beginning.

“;It is dangerous for us if a guerrilla force has an income,”; said Daoud, who as deputy interior minister has responsibility for counternarcotics efforts.

Drug smugglers with an eye to Kunduz's border with Tajikistan have jumped into an alliance with the Taliban to create instability that allows their illegal business to thrive, he said.

The former Taliban government was so harsh that many Afghans offered little resistance. “;What surprises is how easily people capitulate when they come because the memories are so fresh,”; the Western official said.

Shoaib, 25, a villager from the Archi district who moved to the city of Kunduz to find work, said: “;We are forced to be happy with the Taliban. They force the people in each street to prepare 10 guns and men. They say come and do jihad.”;