The Bush administration on Wednesday warned of "real consequences" for Iraq if it rejects a newly negotiated security pact.

Without a deal, the United States could be forced to end its military operations.

The White House said Iraqi security forces are incapable of keeping the peace without U.S. troops, raising the specter of reversals in recent security and political gains if the proposed security deal is not approved by the time the current legal basis for U.S. military operations expires Dec. 31.

"There will be no legal basis for us to continue operating there without that," White House press secretary Dana Perino said. "And the Iraqis know that. And so, we're confident that they'll be able to recognize this. And if they don't, there will be real consequences, if Americans aren't able to operate there."

At the Pentagon, press secretary Geoff Morrell said the U.S. fallback position is to extend the U.N. Security Council mandate authorizing U.S.-led coalition operations in Iraq, but he emphasized that the Bush administration's preference is to complete a bilateral U.S.-Iraqi agreement.

"Our focus is entirely on trying to get this deal done," Morrell said.

Morrell said Gates has not had direct contacts with Iraqi officials since Baghdad announced earlier this week that Prime Minister Nouri al-Maliki determined that unspecified changes to the draft accord are required. The spokesman said it was not clear what changes the Iraqis are demanding.

At the State Department, spokesman Robert Wood said time is running short.

"As others have said, the door is closing," Wood told reporters. "It's time for the Iraqis to step up to the plate and take a decision." Wood insisted that the administration had yet to hear anything official from the Iraqi government on its position or its suggestions for possible amendments.

The U.S. has 155,000 troops in Iraq. In addition to conducting combat operations against a weakened insurgency and hunting down Al Qaeda fighters, the U.S. military is training Iraqi security forces, assisting in the resettlement of displaced persons, coordinating efforts to restore and improve basic services like water and sewage, and providing personal security for senior Iraqi government officials.

Iraqi government on Wednesday decried what it called the "not welcomed" statements from Adm. Michael Mullen, chairman of the Joint Chiefs of Staff, who cautioned the Iraqis of unwelcome consequences in the event that the security pact is not signed by the end of the year.

Mullen, who was traveling in Europe, told reporters on Tuesday that time was running out for the Iraqis to sign the deal and that he was concerned the Iraqis may not fully appreciate the seriousness of the situation.

"These statements are not welcomed in Iraq," Iraqi government spokesman Ali al-Dabbagh said in a statement. "All Iraqis realize the volume of their responsibilities and they appreciate the importance of signing the pact or not in the way they deem it proper."

Al-Dabbagh added: "A compulsory method must not be imposed on their choice and it is improper to address Iraqis in such manner."

Morrell said the Iraqis should not take Mullen's comments as an attempt to force anything on them.

"That couldn't be further from the truth," Morrell said. "We are not trying to pressure the Iraqis or force the Iraqis into signing anything they don't wish to sign."

In subsequent remarks Wednesday, Mullen said he believes the Iraqis are not ready to provide their own defense, according to a Pentagon account of comments to reporters traveling with him.

Mullen also made clear in those remarks that if there is no U.S.-Iraqi deal and the U.N. mandate runs out on Dec. 31 without being extended by the Security Council, then all U.S. military operations would have to cease. Mullen and other senior U.S. military officials have said repeatedly that the security situation in Iraq is too fragile to justify a full U.S. withdrawal anytime soon.

The proposed security pact calls for all U.S. combat forces to be removed from Iraqi cities by June 2009 and for all forces to leave the country by the end of 2011, unless both sides agree to an extension.

In a satellite video-teleconference from Baghdad, an Army commander told reporters at the Pentagon on Wednesday that his understanding is that by June 2009 U.S. troops would not be based inside cities but would be allowed to operate as trainers and advisers attached to Iraqi military units.

"We will have embedded teams," Col. William Hickman, commander of the 2nd Brigade, 101st Airborne Division, said. "And those teams will remain with Iraqi army and the Iraqi police in execution of our mission. So that is how we're seeing our situation here — to continue to focus on the training of the Iraqi security forces so that they are prepared as we go into spring and summer of next year."