Citing shortcomings that set back the last big U.S.-led offensive in neighboring Helmand province, General Stanley McChrystal said he wanted more time to shore up Afghan support for the Kandahar campaign and to prepare local authorities to provide government services when security improves.
The decision to move more slowly on what has been billed as the biggest operation of the nearly nine-year-old war adds to doubt about what can be achieved by this year's end, when the White House is holding a review and demanding signs of progress.
U.S. Defense Secretary Robert Gates said gains would need to be seen by then in order to maintain public support for the war in NATO countries, which has eroded as the death toll has soared. At least 17 foreign troops have been killed this week.
The massive military operation in Kandahar is the linchpin of McChrystal's strategy to turn the tide this year, using the bulk of 30,000 reinforcements sent by U.S. President Barack Obama in a final "surge" of extra troops announced in December.
U.S. commanders had initially seen the main thrust of military operations in Kandahar running from this month to the beginning of August, before the Muslim holy month of Ramadan, according to an internal schedule seen by Reuters in March.
"I do think that it will happen more slowly than we had originally intended," McChrystal told reporters on the sidelines of a NATO meeting in Brussels. "But I don't think that's necessarily a bad thing. I think it's more important we get it right than we get it fast."
He did not detail a revised Kandahar schedule, but said it would take a number of months "for this to play out," with "significant" operations now expected to continue after Ramadan.
Asked if the United States would know by the 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."
NATO Secretary-General Anders Fogh Rasmussen brushed aside suggestions the campaign was faltering. The alliance was "making a lot of progress" although member-states should be ready for a "very tough time in the coming weeks and months" as extra troops pour into Taliban strongholds in the south, he said.
Obama has embraced a counterinsurgency strategy devised by McChrystal last year that aims to push the Taliban from key population centres. But in agreeing to send McChrystal extra troops, the White House also set a goal of starting a gradual drawdown in July 2011, making the next 12 months critical.
McChrystal said he wants to make sure local leaders are on board before launching the Kandahar operation.
"We really want the people to understand and literally pull the operation toward them as opposed to feel as though they are being forced with something they didn't want," he said.
The changes in Kandahar plans also reflect lessons learned by the U.S. military during the offensive earlier this year in Marjah, a rural area of Helmand, the biggest operation of the war so far, which proved more difficult than expected.
"More prep" would have helped in Marjah, particularly when it came to ensuring Afghans were ready to step in and provide government services, McChrystal said. "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 said he still envisaged a gradual campaign in Kandahar aimed at delivering security and governance, as opposed to one big military assault.
"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."
The fragility of the security situation in Kandahar was underscored on Wednesday when at least 40 people were killed by a suicide bomb attack on a wedding party north of Kandahar city.
McChrystal said the growth of Afghan security forces has accelerated and the quality of recruits has improved, although some experts dispute that. Rasmussen called for NATO members to help fill a shortfall in trainers for Afghan forces, saying they were key to transferring authority to the Afghans.