The top U.S. military officer said Friday that the Pakistani military may be able to shut down Taliban hide-outs on its soil to prevent insurgents from moving back and forth across the long, porous border with Afghanistan. A day after President Barack Obama released a review of the U.S. war strategy, Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, told reporters in Kabul that fixing the problem is critical to making progress in the war. But he said he's encouraged by what Pakistan has already done to go after insurgents on its side of the border. "I certainly think it is very possible that the Pakistani military will achieve the goal," he said. A five-page public summary of the White House's classified Afghanistan war review said dealing with havens would require greater cooperation with Pakistan along the border. The areas of most concern -- the Pakistani provinces of North Waziristan and Baluchistan -- are not mentioned by name. Pakistan has made progress against havens over the past year, the summary said. But Pakistani authorities have focused on militants who pose a threat inside Pakistan. Authorities have refused a U.S. request to take on militants in North Waziristan, which is used most often to target U.S. forces. U.S. military officials have been working to counter assertions by U.S. intelligence officials that the war in Afghanistan cannot be won unless Pakistan eliminates the sanctuaries and that Pakistan has decided not to do so. Gen. David Petraeus, the top commander of U.S. and NATO forces, praised Pakistan's efforts.