I think two years is too long, but why would the Bush Administration reject this offer out of hand? Because it sets a timetable? How many years do they expect it will take for the Iraqi Army/Police to be able to defend themselves? And who are they supposed to defend themselves from if the insurgents are willing to stop their attacks? Link below; my emphasis.
“Eleven Sunni insurgent groups have offered an immediate halt to all attacks - including those on American troops - if the United States agrees to withdraw foreign forces from Iraq in two years, insurgent and government officials told The Associated Press on Wednesday.
Withdrawal is the centerpiece of a set of demands from the groups, which operate north of Baghdad in the heavily Sunni Arab provinces of Salahuddin and Diyala. Although much of the fighting has been to the west, those provinces are increasingly violent and attacks there have crippled oil and commerce routes.
The groups who've made contact have largely shunned attacks on Iraqi civilians, focusing instead on the U.S.-led coalition forces. Their offer coincides with Prime Minister Nouri al-Maliki's decision to reach out to the Sunni insurgency with a reconciliation plan that includes an amnesty for fighters.”
http://www.guardian.co.uk/worldlatest/story/0,,-5917866,00.html