KABUL (Reuters/AFP) - Personal grievances, battle stress, and domestic problems are behind more attacks by rogue Afghan security forces on Nato troops than are Taliban infiltrators, the coalition said on Monday.

Western forces have stepped up security to prevent more attacks, after the killing of 17 foreign soldiers by Afghan security personnel this year, NATO spokesman Brigadier General Carsten Jacobson told reporters.

In some cases, that includes increased protection on hand in case more Afghans turn their guns on Western mentors. A series of insider attacks has raised doubts over the ability of local forces to take over security responsibility.

“The vast majority (of reasons for attacks) lie in the individual. Personal reasons, personal grievances are one of the major causes,” Jacobson told reporters.

“One of the things that we are finding is that in many cases there were signs and symptoms that could have been seen, and leadership has to be improved to make sure that those signs are seen in the future, in time before an incident happens.”

The rise in insider attacks on foreign soldiers has stoked fears that either Afghan soldiers and police have turned against their colleagues, or the security force has been infiltrated by Taliban insurgents.

Last month, an Afghan general said the Taliban have a sophisticated system in place to breach Afghanistan’s security forces.

Meanwhile, NATO’s chief denied on Monday that the alliance was speeding up the withdrawal of combat troops from Afghanistan as he sought to clear up “confusion” over the pullout planned for the end of 2014.

Secretary General Anders Fogh Rasmussen insisted that NATO was sticking to the timeline agreed at the Lisbon summit in November 2010 after recent comments from Western and Afghan officials indicated that 2013 was a new target.

“There is nothing new in all this but maybe it is necessary to clarify these timelines because sometimes they are mixed up in a way that creates some confusion,” Rasmussen told a news conference.

Rasmussen explained that to complete the transition of security responsibility to Afghan forces nationwide by the end of 2014, control of the last provinces must be handed over in the middle or the second half of 2013.

“That’s why the year 2013 has suddenly been mentioned,” he said.

“It’s not about accelerating the transition process, but it’s actually in order to stick to the Lisbon roadmap that we have to take 2013 into account,” he said.

It takes 12 to 18 months to complete the transition of provinces to Afghan forces, he noted. Afghan security forces are in the lead in provinces representing half the country’s population, including the capital Kabul.

Before meeting with NATO counterparts in February, US Defence Secretary Leon Panetta had indicated that US troops would switch to a training role in 2013, but later stressed that they would continue combat through 2014.

Afghan President Hamid Karzai told Panetta last month that international forces should leave villages and that NATO should handover to Afghan forces in 2013.

Karzai’s office later appeared to step back, saying the demand was nothing new.

The way forward in Afghanistan, including the alliance’s role after 2014, will be discussed at a NATO summit in Chicago in May.

“We will not abandon Afghanistan,” Rasmussen said, adding that NATO will continue in a training and advisory role and would help fund the Afghan security forces after 2014.