The new U.S. ambassador to Iraq Ryan Crocker takes an oath during a ceremony held at the U.S. Embassy in Baghdad March 29, 2007. (Xinhua Photo)
 
The new U.S. ambassador to Iraq, Ryan Crocker, was sworn in at the U.S. Embassy in Baghdad's heavily fortified Green Zone on Thursday.

The swearing-in ceremony was held at the embassy, which once was Saddam Hussein's former Republican Palace, and was attended by U.S. Lieutenant General David Petraeus, the head of U.S. forces in Iraq, and embassy officials, U.S. Embassy spokesman Lou Fintor said.

Crocker told the ceremony that his country is facing "historic challenges" in Iraq with insurgents and militia continue to threaten security in Baghdad and around the country.

"These challenges will demand a strong commitment and broad performance from the Iraqi government and the international community," Crocker said.

He emphasized that his mission in Iraqi is not impossible, saying "all of these (challenges) will be very hard but if I thought it was impossible I would not be standing here today."

The 57-year-old ambassador pledged to support the government of the Shiite Prime Minister Nuri al-Maliki, but warned that the Iraqi leader must take all necessary steps to unite the war-torn country.

"We must stand by the Maliki government and all Iraqis who seek a better future and remain committed to their success," Crocker said.

"This government, under the leadership of Prime Minister Maliki, must continue to take the necessary steps to unify this country, and to deliver tangible improvements to the lives of all Iraqis," he added.

Crocker, who arrived in Iraq late on Tuesday, replaced Zalmay Khalilzad, who left the country earlier this week. Crocker will present his credentials to Iraqi President Jalal Talabani soon, Fintor said.

U.S. President George W. Bush has nominated Khalilzad to be U.S. ambassador to the United Nations.

Editor: Yan