* Security in cities reported "dramatically improved"
* Progress toward fully independent Afghan military "incremental"
* Safe havens, corruption, weak governance are key threats
By David Alexander
WASHINGTON, Dec 10 (Reuters) - Attacks by Taliban insurgents rose slightly during the main part of the Afghan fighting season this year as some U.S. forces withdrew and the transition to a lead role for Afghan security forces picked up pace, according to a Pentagon report released on Monday.
The report to Congress downplayed the rise in violence, saying the key measure was a dramatic increase in security in the country's main cities. While acknowledging the Taliban can still carry out attacks at the same levels as last year, the report said the greatest threats to stability were elsewhere.
"The insurgency's safe havens in Pakistan, the limited institutional capacity of the Afghan government and endemic corruption remain the greatest risks to long-term stability and sustainable security in Afghanistan," said the semi-annual Pentagon progress report on Afghanistan.
U.S. officials, briefing reporters on the document, said training of Afghan military and police forces was on track for them to take the lead security role nationwide by next summer.
The strategy guiding international forces calls for Afghans to take the security lead next year and full security responsibility by the end of 2014, when most foreign combat forces are due to withdraw.
About 76 percent of the population now lives in areas where Afghan police and troops have the lead role for security, the report said. Planning is under way to transfer additional parts of the country to Afghan security leadership.
So far, very few Afghan units are fully independent from international forces. While some units are capable of carrying out independent operations, they often have to rely on the NATO-led coalition for air power, intelligence and other specialized skills.
A senior U.S. defense official, speaking on condition of anonymity, said only "a very small percentage" of Afghan units are capable of fully independent operations at this point, "but that's all we would expect right now."
While progress toward full independence is "incremental," the official said, "In terms of the operations that they have to carry out day to day, (they) may be doing those independently all the time."
The report attributed the rise in Taliban attacks between April and September to the increased pace of combat and to a poor, shortened poppy harvest, which freed low-level insurgents to begin the fighting season early.
MORE ATTACKS IN RURAL AREAS
Taliban-launched attacks rose by 1 percent between April and September compared with 2011, the report said. But the increased violence took place mainly in rural areas, with security "dramatically improved" in all but one of the country's five most populous districts, the report said.
Overall since the start of the year, Taliban attacks were down 3 percent, the report said. During that period they fell 22 percent in Kabul compared to 2011, 62 percent in Kandahar, 13 percent in Heart and 88 percent in Mazar-e-Sharif. They were up 2 percent in Kunduz.
The senior defense official said violence in Afghanistan remained higher than it was in 2009, before the United States sent in 33,000 additional troops to try to counter Taliban advances. Those 33,000 troops withdrew over the course of the year and U.S. forces are now back to the 2009 level of 66,000.
"Even though the violence remains high, the fact that it's in the less populated areas shows that it's less effective violence, less effective in terms of altering the view of people in Afghanistan as to where their future lies, whether it lies with the Taliban or with the government," the senior U.S. defense official said.
"If you travel around any of the cities in Afghanistan, particularly, say, Kandahar city, now as opposed to 2009, it's a completely different experience," the official said.
Several security issues remained challenging for international forces, especially the increasing number of attacks on foreign troops by members of the Afghan military, the report said.
"The rise in insider attacks has the potential to adversely affect the coalition's political landscape," it said.
The senior defense official said international and Afghan forces had been able to prevent the Taliban from regaining any significant territorial control during the fighting season.
As in last year, the Taliban has been urging its forces, particularly the leaders, to stay the winter in Afghanistan and step up the fight to make up for their inability to regain lost ground, the official said.
"While they are giving that message to their troops, to their forces, we don't see that actually happening on the ground," the official said.