Visiting U.S. Vice President Dick Cheney says the United States has made a "successful endeavor" in Iraq on the eve of the fifth anniversary of the U.S. - led invasion.

He says there is a significant progress compared with 10 month ago, adding security has improved dramatically and the Iraqi leaders have made progress in governing.

"I think given the enormous efforts that have been made, the sacrifice that has been made, both in terms of life and national treasure, the succeeding in Iraq is very very important. We are succeeded; we are not quit, before the job is done."

Cheney made the trip three days ahead of the fifth anniversary of the Iraq war that falls on March 20.

Nearly 4,000 U.S. troops have died since the beginning of the war. About 90,000 Iraqi civilians have been killed over the past five years, according to Iraqbodycount, a Website that traces the Iraqi war casualties.

In addition, some 4 million Iraqis are still displaced, and the International Committee of the Red Cross says in a report that millions are still deprived of clean water and medical care.