Will Iraq disintegrate if the United States withdraws its troops?

The United States and Iraq are close to agreeing a security accord under which the US would pull its combat troops out of Iraqi cities, towns and villages on 30 June 2009, and out of Iraq by 31 December 2011. This will only happen if a joint Iraqi-American ministerial committee agrees that security in Iraq has improved to the point where the half million strong Iraqi security forces can take over.