Defense Secretary Robert M. Gates today signaled sharply lower expectations for the war in Afghanistan, warning the conflict will be "a long slog" that U.S. and allied military forces - even at higher levels - cannot win alone.

    Gates said the U.S. military expects to be able to send three additional combat brigades to Afghanistan from late spring through midsummer to fill a security vacuum "that increasingly has been filled by the Taliban."

    Still he said that he would be "deeply skeptical" of any further U.S. troop increases, saying that Afghan soldiers and police must take the lead - in part so that the Afghan public does not turn against U.S. forces as they have against foreign troops throughout history.

    U.S. goals in Afghanistan must be "modest" and "realistic," Gates said in his first congressional testimony as Pentagon chief under President Obama. "If we set ourselves the objective of creating some sort of central Asian Valhalla over there, we will lose, because nobody in the world has that kind of time, patience and money," Gates testified before the Senate Armed Services Committee. Valhalla is used as a synonym for heaven, but in Norse mythology it is a great hall where heroes slain in battle are received.

    Civilian casualties resulting from U.S. combat and airstrikes have been particularly harmful to progress in Afghanistan and must be avoided, Gates stressed. "My worry is that the Afghans come to see us as part of their problem rather than part of their solution; and then we are lost."

    Gates also warned of Iranian interference in Afghanistan, pointing to a slightly increased flow of weapons and components of lethal munitions known as "explosively formed projectiles." He said Iran wants to "have it both ways," seeking economic and diplomatic benefits of relations with Kabul while trying to impose "the highest possible costs" on U.S. and coalition troops.

    Iranian activities have been troubling in other parts of the world, he said, including Latin America, where he said Iran is setting up "a lot of offices and a lot of fronts."

    "Iranian meddling is a concern" there, he said.

    On Iraq, Gates said Pentagon and military leaders are working on several timetables for U.S. troops to move from a combat to an advisory role beginning as early as 16 months from now and extending until the end of 2011. The options and their risks are being presented to Obama, who will meet with the Joint Chiefs of Staff at the Pentagon tomorrow to hear their views, Gates said.

    At the Pentagon his priority will be to reform the cumbersome acquisition process, he said, while crafting "a unified defense strategy that determines our budget priorities."

    "The spigot of defense spending that opened on 9/11 is closing. With two major campaigns ongoing, the economic crisis and resulting budget pressures will force hard choices on this department," he said.

    In particular, he criticized "entrenched attitudes throughout the government" that he said "are particularly pronounced in the area of acquisition: a risk-averse culture, a litigious process, parochial interests, excessive and changing requirements, budget churn and instability, and sometimes adversarial relationships" between the Pentagon and other parts of government.