It's bizarre, I know, but it seems the US had hoped that peace-keeping would be a cakewalk or international forces would flood into Iraq after the war to relieve US occupying forces. Obviously, after going it alone, insulting half the world, and ranting about "punishing" some of the world's most powerful nations (Russia, Germany, France, China, etc.), the US has found itself isolated with some heavy-lifting ahead and with little hope of relief.
We still have allies in the hugh Coalition of the Coerced. But if you throw your lot in with Uzbekistan, Ethiopia and Eritria, don't expect tens or hundreds of thousands of international troops to help bail you out with the occupation. And given that Iraq is nowhere even close to being pacified, no one can truthfully be expected to be willing to replace American GIs in the crosshairs.
Not to mention that many potential US allies are already stationing forces in Afghanistan (NATO will be sending 5,500 troops for peacekeeping duties in that now-forgotten nation).
The US has gotten committments for only 13,000 troops, and Britain has already pulled 20,000 from the country. The net result? The US will not be able to relieve the troops that did most of the fighting and dying during the active phase of the war.
The Army's 3rd ID, in fact, will be placed back in combat duty, despite the fact it is combat inoperative thanks to a lack of spare parts. A preview of the difficulties ahead, today US forces faced uprising in the small town of Hit, and were forced to withdraw outside the town.
With friends like the Bush Administration, our troops don't need enemies. But not to fear, the 'adults' are now in charge.