I share the concerns of Robert Kagan and William Kristol, who warned on these pages this week that the deteriorating situation in Iraq could well lead to failure with disastrous consequences. But the solution they propose flies in the face of reality. They call for increasing US force levels in Iraq by some 50,000 troops. Given the current state of US ground forces, this is just not possible, certainly not in the short term.

America’s current force level in Iraq is about 140,000, including National Guard and Army Reserve elements and US Marine Corps units. To sustain such a force requires a rotation base of some two or three times this size. For every unit engaged in operations, there is one preparing to deploy as a replacement for the returning unit, and one recently returned to the US for re-equipment, training of new personnel and time spent with families.