In such a situation, stemming violence early is critical. Checkpoints need to be manned, curfews enforced, vigilantes arrested or shot, mosques and schools and hospitals protected.
Yes, Iraqi forces can do many of these things and should. And, yes, many of them will. But Iraqi security forces are at present politically untested. Most units are dominated by one group or another. If the country begins to descend toward civil war, the temptation of many will be to take sides in the sectarian strife rather than stop it.
The foreign coalition can do a great deal to discourage this. By deploying with Iraqi police and army troops on the streets, it can provide enough manpower to do the labor-intensive work required to restore order as anarchy begins to spread. It can help give Iraqi security forces the backbone they need to hang together and do their job for the country rather than fight for their Kurdish or Shiite or Sunni Arab interests. It can act as a glue, helping to hold them together by working with them and providing an example worthy of emulation.”