As Juan Cole points out, 3,000 US troops in Iraq are not troops, they are hostages.
If the troops are attacked it is likely to result in more troops being sent in and a possible third US-Iraq war. Besides which many Iraqi's do not want them there:
The Muqtada al-Sadr nativist Shiite movement in Iraq is planning a huge demonstration in downtown Baghdad on Friday, in favor of three demands. The first is that the Iraqi government announce an immediate jobs program that would put 50,000 Iraqis to work, from all ethnicities and religious groups. The second is that the Iraqi government give each Iraqi a royalty payment on Iraqi oil profits (ironically a suggestion once made by US viceroy in Iraq, Paul “Jerry” Bremer and modeled on a program in Alaska). The third is that there be no US troops at all in Iraq by the end of the year or earlier.These are not idle demands:
The Sadrists not only have a proven ability to put a lot of people in the streets, but their some 40 seats in parliament are key to the governing coalition of Prime Minister Nouri al-Maliki, so that he ignores them to his peril. The Iraqi constitution allows for parliament to call for a vote of no confidence if 50 MPs sign off on it, and rivals of al-Maliki such as Ayad Allawi have been calling for early elections.Meanwhile the US establishment is busy debating with itself how many troops the US should keep in Iraq as if it was their decision to make.
The report brought howls of outrage from Senators John McCain and Lindsey Graham, who say they want to keep 25,000 troops in Iraq. I am not sure why McCain and Graham believe that this decision is their own. The only legal document governing this issue is a Status of Forces Agreement signed by the Iraqi parliament and the Bush White House in late 2008, which stipulates that there must be no US troops in Iraq at all by December 31 of this year.Their reason? Iran. Seems that McCain and Graham have completely failed to notice that in the wake of the 2010 elections, Iran chose the Iraqi government. One of the (many) reasons I opposed the invasion of Iraq in the first place was that it would inevitably increase the influence of Iran.
The US presided over the destruction of a Sunni-dominated secular Arab nationalist regime and the installation of a government led by fundamentalist Shiites, many of whom had lived in exile in Iran and had excellent relations with Tehran. That cow is out of the barn, and the presence of US troops is unlikely to be relevant to the budding Tehran-Baghdad-Damascus axis, which is a political reality.
