"You don't fight terrorists with large armies. "
No, but you do secure countries, which is a necessity for success in Iraq.
They don't need more of our troops to secure their country. To the extent that it can be done at all, they can do it pretty much by themselves at this point.
Of course, they are going to face terrorism for another decade or more, but sending more US troops to walk their streets isn't going to change that.
Wrong-o. You can post US soldiers on every damn street corner, and it will only do 2 things:
/1/ Provide more American targets for snipers and bombers, and
/2/ Postpone ("enable") the day that the Iraqis are forced to step up to the plate and deal with the terrorists and provide their own security.
500,000 troops in Iraq would be a monumental blunder, as it was in Viet Nam, when the conventional-minded ground-pounder generals decided that the Special Forces and counterinsurgency troops weren't "winning the war fast enough."
You want to see a real quagmire, send in 500,000 troops.