The new American commander in Afghanistan said Wednesday that U.S. Marines had faced less resistance than expected in their operation to clear Taliban safe havens in the south, but that British troops just to the north were running into fiercer fighting than anticipated. The commander, Gen. Stanley A. McChrystal, also said that he was surprised by the resilience of pockets of Pashtun militants in western and northern Afghanistan, areas that he expected to be relatively calm but that now needed more troops and stronger local governance. McChrystal's assessment one month into his command does not only reflect the dynamic and unpredictable nature of the fight in Afghanistan. It also underscores the challenges facing American commanders and diplomats as they work with allied and Afghan officials to carry out the Obama administration's new war strategy here. In the pivotal southern province of Helmand, for instance, where 4,000 Marines and 650 Afghan soldiers faced only sporadic fighting in the first two weeks of their operation, McChrystal said Taliban fighters were starting to fight back, probing with small-scale attacks and improvised explosives. 'They're coming back and nipping at the edges,' McChrystal said in a 40-minute interview on the wood-deck patio outside his heavily guarded headquarters here. 'They're waiting to see what happens.' American commanders had predicted a sharp rise in casualties as U.S. troop levels rose toward the 68,000 planned by year-end. McChrystal warned against expecting any quick end to the combat in the south, the Taliban heartland. 'I think we're talking months for this to play out, and it'll play out at a little different speed everywhere,' the general said. 'Until we hit the point where the insurgent fighters decide they cannot force us out or cannot discourage us, I think they're likely to stay significantly.' McChrystal said the operation's next stage would be to expand to other important towns in the southern Helmand River valley, to clear out militants there, and hold the reclaimed ground until Afghan civilian authorities and officials could take charge. But moving into these new areas will require more Afghan police officers and soldiers than are currently expected to be available, McChrystal said. As part of a 60-day mission review, the general said he would recommend expanding the Afghan army, now scheduled to increase to 134,000 troops. He said he would also seek to speed the process to do that before the scheduled completion date of 2011. 'The key to this is Afghan responsibility to the fight,' he said. 'As a team, we are better.' McChrystal declined to say whether he would also recommend expanding American combat forces or increasing the number of military trainers, but he did not rule it out. The new American command team is facing a number of other problems. Pockets of Pashtun insurgents are stirring up trouble near Kunduz, in northern Afghanistan, where German troops patrol, and in Farah province, in the western part of the country, where Italian soldiers are assigned. One senior American military officer here, who spoke on condition of anonymity because he was not authorized to speak publicly, said Kandahar, the country's second largest city, was 'under stress' from Taliban fighters. Aides said McChrystal was seeking to bring the same high-speed tempo and precise synchronization that were hallmarks of his terrorist-hunting days as head of the military's Joint Special Operations Command to his new position. But problems still need ironing out. 'We lack coordination as an organization,' the senior military official said. 'We've been fighting five regional fights. We haven't been fighting one war.' Asked whether he was getting the cooperation he wanted from Pakistani forces in combating the main Taliban network based in Quetta, Pakistan, which controls much of the Taliban activity in southern Afghanistan, McChrystal paused several seconds before answering. American officials have long expressed frustration at what they see as Pakistani inaction against a major threat to American forces in Afghanistan. 'It's my intended desire to work with the Pakistani military and government to try to reduce that' inaction, he said. McChrystal said his ultimate task was to win over a majority of the Afghan public, many of whom are angry and distrustful of the Americans after nearly eight years of war and all too many errant airstrikes that have killed civilians. The general said the Taliban's use of roadside bombs would eventually 'boomerang,' because 80 percent of the bombings harmed Afghans, and more than half of the attacks killed and wounded civilians. 'At the end of the day, you're fighting for the population, not with the population or against the population,' McChrystal said. 'As you fight for them, you are trying to convince them. You are in an argument with the enemy over the population, and they are listening, and they are watching what you do and what you say. They are going to decide based on who makes the most convincing argument.' 'Are you protecting them? Can you stop them from being coerced at midnight by an armed man who shows up and threatens them?' the general continued. 'It's a retail war.' 