Updated

President Bush pledged Monday that security gains will continue in Iraq but offered no new details about how that promise will affect the timing of additional U.S. troop withdrawals.

In thanking Lt. Gen. Ray Odierno, who until recently served as the No. 2 commander in Iraq, Bush said, "The gains that you and your teams have made will continue on, because stakes in Iraq are essential for peace, essential for freedom, and essential for the security of this country."

For the past 15 months, Odierno was the top day-to-day commander in Iraq under Gen. David Petraeus. He oversaw the buildup of military forces that Bush ordered in January 2007. That troop expansion, now being phased out, is credited with improving security and stability in Iraq.

Trying to summarize Odierno's role in that success, Bush said: "I appreciate the fact that you really snatched defeat out of the jaws of those who were trying to defeat us in Iraq."

Odierno has been nominated for promotion to four-star rank and assignment as vice chief of staff of the Army. His post is pending Senate confirmation. Odierno remains the commanding general at Fort Hood, Texas.

There currently are about 158,000 U.S. troops in Iraq, and signs continue to point to a suspension in the drawdown of U.S. forces this summer.

For now, Bush says his decision on bringing more U.S. troops home will be based on how such a move will affect success in Iraq. He says he won't reach a conclusion until he hears from Petraeus, Defense Secretary Robert Gates and the Joint Chiefs of Staff. In the Oval Office, Bush thanked Odierno for advice on how to proceed but said the guidance was "not necessarily with troop levels, because that study is going on now."

The military began sending an additional five Army brigades to Iraq in 2007 to back a new approach to countering the insurgency.

Security has improved markedly since last summer, when the last of those brigades arrived in Iraq, adding 30,000 troops to reinforce the military strategy of protecting the Iraqi population and undercutting the viability of the insurgency. After reaching a strength of 20 brigades in late June, the first of the five extra brigades went home in December without being replaced, and four more are scheduled to leave by July.

Petraeus is expected to recommend to Bush in April that he wait about four to six weeks — after the troops involved in the buildup return home by July — before deciding whether any more troops could be withdrawn. Over the weekend, Bush declined to promise more U.S. troop withdrawals from Iraq before he leaves office, and underscored the need for a strong military presence during Iraqi provincial elections in October.

Also Monday, a top U.S. commander in northern Iraq said it will take months more of fighting to drive al-Qaida insurgents from Iraq's city of Mosul, the third largest in the nation.

Army Brig. Gen. Tony Thomas said coalition forces are "pursuing a disrupted but still dangerous enemy" in northern Iraq, the center of activity for an al-Qaida-led militants there by coalition operations elsewhere in Iraq.

Iraqi Prime Minister Nouri al-Maliki has promised a "decisive battle" against the network there. The U.S. military has tried to temper expectations, warning it would not be a swift strike, but rather a grinding campaign that will require more firepower.

Speaking to Pentagon reporters from a military base outside Tikrit, Thomas, second in command in the north, said the effort would take months.

"This will be a steady, methodical coalition and Iraqi security forces campaign to eliminate the enemy from Mosul," Thomas said by video conference.

Asked how much of Mosul is now under coalition control, Thomas said it was hard to quantify but that coalition forces "are slowly but surely eliminating (the militants') toehold in the city."

One-half to two-thirds of attacks in Iraq today are in and around Mosul, officials have said.