In September, General George Casey, the senior American military commander in Iraq, testified to Congress that modern insurgencies last about a decade, and that the Iraqi army had only one battalion capable of fighting without help from American military forces. A month later, the influential International Institute for Strategic Studies in London estimated that US troop withdrawals next year were likely to be small, and that it would take at least five years for Iraq to build the 300,000-strong army needed to fight the insurgency on its own.