US military personnel in Iraq and Afghanistan faced a difficult challenge. The soldiers and marines needed to combat a vicious, irregular force of insurgents. At the same time, utmost care had to be taken to avoid civilian casualties. Avoiding collateral damages was easier said than done. Senior US military leaders like Admiral Mike Mullen, General Stanley McChrystal, and General David Petraeus implemented a number of doctrinal changes to avoid civilian casualties. But changing the mindset and training of US soldiers was not an overnight task, especially when restraints on the use of force put US personnel at risk.