KABUL—The commander of coalition forces in Afghanistan said the offensive in Kandahar is going more slowly than expected, in part because it still lacks the wholehearted support of the local population.

U.S. Gen. Stanley McChrystal's warning, delivered in Brussels at a meeting of North Atlantic Treaty Organization members, is the latest effort by military leaders to play down hopes for rapid progress in Afghanistan, where U.S. President Barack Obama would like to begin a drawdown of troops in July of 2011. The U.S.-led coalition has been ramping up operations in turbulent southern provinces since spring, with 30,000 additional U.S. troops to arrive this year.

Troops first focused on cleaning out Taliban strongholds in Helmand and were expected this summer to improve security around Afghanistan's second-largest city, Kandahar. "I do think that it will happen more slowly than we had originally anticipated," Gen. McChrystal told reporters at the NATO conference. "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."

Gen. McChrystal said the coalition has reined in hopes for quicker progress partly because of continued resistance in neighboring Helmand, where he had vowed to win hearts and minds by quickly delivering residents a "government in a box."

More than three months after NATO troops moved into the Taliban bastion of Marjah, insurgents continue to hold sway over much of the populace.

"In Helmand River Valley, we are reminded that it's a deliberate process," Gen. McChrystal said. "It takes time to convince people." Casualties among coalition troops have surged in recent weeks, amid a steady stream of bombing attacks and ambushes, primarily in Kandahar and Helmand.

Meanwhile, Afghan President Hamid Karzai has continued to be an unpredictable partner; this week he abruptly fired two top security officials, both of whom had worked closely with coalition forces.

While NATO said there was no formal start date for the Kandahar offensive, serious operations were expected to begin in June. The start was delayed after Mr. Karzai promised a gathering of elders in May that no military operation would begin without their assent.

Only a small part of the new U.S. forces ordered to Kandahar under the surge plan announced by Mr. Obama in December has actuallyarrived in the volatile province. Volcanic ash that disrupted air traffic in Europe and other logistic mishaps have contributed to the delay.

U.S. officials say the current focus is on improving governance in the city. Besides adjusting their timing, coalition officials have sought to downplay expectations of a decisive offensive that could cause insurgents to turn tail and run. Instead they have talked of a political and military "reshaping" of the climate in Kandahar. Gen. McChrystal said Thursday that "we've begun extensive planning and shaping operations, and that's ongoing." A fundamental problem in Kandahar, considered the birthplace of the Taliban movement, is that many Kandahar residents don't consider the Taliban to be enemies.

Coalition commanders have planned to root out insurgents from Taliban-controlled parts of districts around Kandahar before moving to reassert government control in the city itself. That plan won't see fruition for another two or three months, officials say.

Gen. McChrystal also is looking for help from NATO members. Coalition officials worry that Afghan security forces are being expanded too quickly to ensure quality in their ranks. Gen. McChrystal observed that the Afghan national police is especially fraught with problems, and that "in many cases, doesn't have as much trust of the populace that a police force must have." The Afghan Army, he said, is making progress, "but they're still a force in development."

Military officials say a timetable for success in Afghanistan is becoming important amid signs that public patience for the war is running thin. U.S. Defense Secretary Robert Gates warned ahead of the NATO meeting that public support for the war will evaporate unless the nations leading can show by the end of this year that the war is not locked in stalemate.

"All of us, for our publics, are going to have to show by the end of the year that our strategy is on the track, making some headway," Mr. Gates said.

Asked if the United States would know by the end of the year whether the operation in Kandahar was successful, Gen. McChrystal said, " I think it will be very clear by the end of the calendar year that the Kandahar operation is progressing. I don't know whether we'll know whether it is decisive."

British Prime Minister David Cameron, meanwhile, on Thursday made his first trip to Kabul since his election and had his helicopter diverted following a "security report" that suggested a threat to his life, a person familiar with the matter said. Intelligence suggested he could be targeted in a rocket attack, according to wire reports.

A Downing Street spokesman said that there had been a "change to the prime minister's original visit schedule," but declined to give details.

Mr. Cameron, who met with President Hamid Karzai had earlier said that 2010 is "the vital year" for the North Atlantic Treaty Organization to show progress in Afghanistan.

He pledged an extra £67 million ($97.37 million) to combat improvised explosive devices that target coalition troops.

The British leader also said that increasing U.K. troop numbers was "not on the agenda" and that he doesn't want British forces to stay in the country a moment longer than necessary. Britain is the second-largest coalition troop contributor after the U.S., with some 10,000 soldiers serving in Afghanistan.

Write to Alan Cullison

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