WASHINGTON, Oct 25 (Reuters) - Crossing the threshold of 2,000 American military deaths in Iraq on Tuesday added to the pressure on President George W. Bush to show progress in Iraq amid waning public support for the war. Bush launched the Iraq war in 2003 hoping for a quick victory with minimal casualties. The Iraqi army was quickly defeated and, when confronted by early attacks by militants, Bush was initially defiant, declaring: "Bring 'em on!" But within months the attacks grew in intensity, bogging down the U.S. force of more than 100,000 troops, aircraft and armor and delaying plans for...