The nation's top military officer said today that more U.S. troops are needed in Afghanistan to help tamp down an increasingly violent insurgency but he does not have sufficient forces to send because of the war in Iraq.

    Adm. Michael Mullen, chairman of the Joint Chiefs of Staff, said insurgent Taliban and extremist forces in Afghanistan have become "a very complex problem" that is tied to the extensive drug trade, a faltering economy and the porous border region with Pakistan. Violence in Afghanistan has increased markedly over recent weeks, and June was the deadliest month for U.S. troops since the war began in 2001, with 28 combat fatalities.

    "I am and have been deeply troubled by the increasing violence there," Mullen said, adding that he has made no secret of wanting to send more forces into the country. "The Taliban and their supporters have become more effective in recent weeks. ... We all need to be patient. As we have seen in Iraq, counterinsurgency warfare takes time and commitment."

    Mullen said military commanders are looking at the prospects for sending additional troops to Afghanistan in 2009, but conditions in Iraq would have to continue to improve for that to happen. The war in Iraq has occupied as many as 20 military brigades during the troop buildup over the past year. The military is reducing that force to 15 brigades this year.

    "I don't have troops I can reach for, brigades I can reach to send into Afghanistan until I have a reduced requirement in Iraq," Mullen said. "Afghanistan remains an economy of force campaign, which by definition means we need more forces there. We have the ability in almost every single case to win from the combat standpoint, but we don't have enough troops there to hold. That is key to the future of being able to succeed in Afghanistan."

    Mullen also addressed the issue of a potential conflict with Iran, saying he clearly favors diplomacy over military action to deter Tehran from seeking nuclear weapons. Mullen visited Israeli officials last week but declined to provide details on his discussions with them.

    "Clearly there is a very broad concern about the overall stability level in the Middle East," Mullen said. For the military, "opening up a third front right now would be extremely stressful on us. That doesn't mean we don't have the capacity or the reserve, but that would be very challenging and the consequences of that are very difficult to predict."

    Mullen said plainly that he opposes the U.S. or Israel engaging Iran with a military strike.

    "My strong preference is to handle all of this diplomatically with the other powers of government, as opposed to any kind of strike occurring," Mullen said. "This is a very unstable part of the world and I don't need it to be more unstable."