American diplomats are trying to negotiate increased UN participation in Iraq. The US does not want to give up control of military forces in Iraq, because the UN has a track record of inept management of peacekeeping operations. The same with Iraqi reconstruction. UN officials have been prone to corruption in reconstruction projects. A lot depends on the nationality of the UN official. The UN gives out senior level jobs to the member nations roughly in proportion to their political power. Some nations provide corrupt candidates, and it is very difficult to remove these officials even when they are caught stealing. UN military leadership also tends to get paralyzed by political squabbles at UN headquarters.
Coalition troops are being worked hard. While there are not a lot of attacks, or attempted attacks each day, this is largely because the troops work so hard to patrol aggressively and professionally and this intimidates and discourages potential attackers. This is the same reason why not attacks have been made on coalition bases. Commanders are concerned that keeping troops in Iraq too long will lead to lower re-enlistments and fewer recruits. There are enough troops to relive current forces after a year, but this does not leave many combat ready units available for any other emergencies. When units return from Iraq, they sort of fall apart as those who enlistments are up leave, and many others who have been scheduled for specialist training or transfer, also leave. New troops have to be trained and integrated into the units. All this turbulence can keep the returning units at only about half its normal combat capability for six months or more.
Ethnic and religious factionalism and violence continues to grow. The trend is driven by local politicians who are eager to increase their own power by harnessing latent fear and hatred of other ethnic and religious groups. This is a pattern seen in Lebanon, Africa, the Balkans, India, Pakistan and, well, everywhere. Except in Iraq there are a lot of guns, and a lot of anger over the atrocious behavior of the Baath Party over the last three decades. One benefit of this animosity, is the growing number of tips on violent plans by factions. Everyone seeks to use the coalition against their enemies. Coalition troops have learned to separate the purely spiteful accusations from the ones that have a basis in fact.