The Marines want a war they can win

This does make some tactical sense in that the Afghani theater contains a lot more of the type of small unit offensive operations the Marines are expert at, while Iraq is more standing army, patrol and control, but I can't shake the feeling the Marines might also be looking for a war they can win.

The Marine Corps is pressing to remove its forces from Iraq and to send marines instead to Afghanistan, to take over the leading role in combat there, according to senior military and Pentagon officials.

The idea by the Marine Corps commandant would effectively leave the Iraq war in the hands of the Army while giving the Marines a prominent new role in Afghanistan, under overall NATO command.

Seemingly, this is what the British are doing, too.