BRUSSELS, June 10 (Reuters) – Military operations to gain control of Kandahar, the Taliban’s birthplace, will roll out more slowly and take longer than initially planned, the top U.S. and NATO commander in Afghanistan said on Thursday.

The shift, outlined by General Stanley McChrystal on the sidelines of a NATO conference in Brussels, is aimed at buying more time to shore up Afghan support for the operation and to build up the capabilities of local authorities to provide services as security improves.

“It’s more important we get it right than we get it fast,” McChrystal told reporters of the Kandahar operation. Though he did not detail the revised timing, McChrystal said, “I think it will take a number of months for this to play out… We want this thing to be as shaped as possible before we go.”

McChrystal’s reassessment puts a spotlight on the limited window available to turn the tide against the Taliban.

U.S. Defense Secretary Robert Gates warned on Wednesday that NATO and Afghan forces will have to show gains by year-end to maintain public support at home and in Europe for the eight-year-old war.

Asked if the United States would know by year-end whether the operation in Kandahar was successful, McChrystal said, “I think we’ll know whether it’s progressing… I don’t know whether we’ll know whether it is decisive.”

McChrystal said the changes in Kandahar reflected lessons learned by the U.S. military during a more difficult than expected offensive earlier this year in Marjah in neighbouring Helmand province.

“As we did it, we found that it’s even more complex than we thought and so we need to educate ourself from that and do it even better in Kandahar,” McChrystal told reporters.

“I want to make sure we’ve got conditions shaped politically with the local leaders, with the people. We really want the people to understand and literally pull the operation towards them as opposed to feel as though they are being forced with something they didn’t want,” he said.

McChrystal said he still envisages a gradual campaign in Kandahar aimed at delivering security and governance, as opposed to one big military assault.

But he said, “I do think that it will happen more slowly than we had originally intended.

“We are already in the process of doing political and military shaping but … I think that the timing in which we can be decisive in the environs around the city will probably happen more deliberately than we had originally laid out.”

U.S. commanders had initially seen the main thrust of military operations in Kandahar running from June to the beginning of August, before the Muslim holy month of Ramadan, according to an internal schedule seen by Reuters in March.

The campaign would have then shifted from a “clearing” phase to a “secure and deliver government” phase, expected to last at least until mid-October.

But McChrystal said “there will be signficant things happening after Ramadan as well”, and made clear he expected to show progress by year-end, rather than complete the operation outright.

In March, Admiral Mike Mullen, the chairman of the U.S. military’s Joint Chiefs of Staff, described Kandahar as Afghanistan’s “center of gravity” and the key to reversing the Taliban’s momentum this year, Obama’s goal when he ordered the deployment of 30,000 extra U.S. troops in December.

But Gates said on Wednesday in London that he believed Kandahar was an important piece of a successful strategy, but not the only piece. “Kandahar and Helmand are important but they are not the only provinces in Afghanistan that matter in terms of the outcome of this struggle,” Gates said. (Editing by Louise Ireland)