MOSUL, Iraq - Defense Secretary Donald H. Rumsfeld, on a Christmas Eve mission to cheer up the troops in Iraq, promised them that no matter how bleak things might look they will look back on their mission with pride.

"There's no doubt in my mind, this is achievable," he told troops in Mosul just three days after the devastating attack on a U.S. military dining hall here.

"When it looks bleak, when one worries about how it's going to come out, when one reads and hears the naysayers and the doubters who say it can't be done, and that we're in a quagmire here, one should recall that there have been such doubters throughout every conflict in the history of the world," he told about 200 soldiers.

Traveling in secrecy amid tight security, Rumsfeld landed in pre-dawn darkness and immediately headed for a combat surgical hospital where many of the victims were treated.

Rumsfeld has made several visits to troops in the region, most recently two weeks ago to a forward base in Kuwait. There, a handful of soldiers openly challenged him about inadequate equipment and long deployments.