From John Kline's remarks on the House floor opposing a nonbinding resolution decrying escalating troop levels in Iraq:
The recent National Intelligence Estimate was even more specific in its analysis. If the United States were to withdraw rapidly, the Iraqi Security Forces would likely collapse; neighboring countries might intervene openly in the conflict; massive civilian casualties and forced population displacement would be probable; and al-Qa'ida in Iraq would attempt to use parts of the country to plan increased attacks in and outside of Iraq.
The Iraqi Security Forces barely function as it is; how would collapse be recognizable? We already accuse Iran and Syria of intervening in Iraq; undoubtedly, Sunni nations are offering their support, as well. Are we really afraid that they'll be more brazen about it? Massive civilian casualties are the reality. Forced population displacement is already a reality.
I, for one, would much rather have al Qaeda setting up camps in Iraq than on the Afghan/Pakistan border. In Iraq, al Qaeda cells would be surrounded by hostile Shia. Their camps would be easily targeted by U.S. armed forces -- no caves, no mountains, no trees.
The best argument against withdrawing troops from Iraq is that leaving now will make conditions on the ground much, much worse. Kline's worst case scenario is already happening.