The UN announced yesterday that its top diplomat in Iraq, Staffan de Mistura, will be leaving his post to become the deputy executive director of the World Food Program. Congratulations are in order for Mr. de Mistura, who is by all accounts one of the best the UN has out there and who has presided over a critical period in Iraq's reconstruction.

Appointed to his post in September 2007, de Mistura had been a close friend and colleague to the original head of the UN mission in Iraq, Sergio Vieira de Mello, who was killed in the tragic August 2003 suicide bombing of UN headquarters in Baghdad. De Mistura's tenure began just as the UN returned was returning full force to Iraq, revamping its mandate to include an ambitious agenda of promoting national reconciliation, supporting elections, and providing humanitarian assistance. As the surge got under way -- and got most of the credit -- in reducing violence in Iraq, it was de Mistura's small UN political mission that brought the credibility and expertise to actually achieve some of the important political goals in a very contentious climate.

Throughout it all, de Mistura and his colleagues have risked life and limb; Iraq is still one of the most dangerous places in the world to work in, and security for UN personnel there remains appallingly thin. His successor will have to address this issue, as well as many other persistent or looming political difficulties, chiefly the solution to the dispute over the oil-rich regions of Kirkuk. We can only hope the UN's new representative in Iraq will do as admirable a job as his predecessors, Sergio and Staffan.