We are at a crucial moment in Iraq. Supporters of the war, like us, have in the past differed over tactics. But at this urgent pass, there can be no doubt that we need to stop the downward slide in Iraq by securing Baghdad. There is no mystery as to what can make the crucial difference in the battle of Baghdad: American troops. A few thousand U.S. troops have already been transferred to Baghdad from elsewhere in Iraq. Where more U.S. troops have been deployed, the situation has gotten better. Those neighborhoods intensively patrolled by Americans are safer and more...