Washington (CNN) -- Pentagon leaders warned Thursday that the United States may lose hard-won gains in Iraq if the State Department can't pick up the slack when American military forces come home.
"Our real worry that all that we have gained is potentially at risk," Defense Secretary Robert Gates told the Senate Armed Services Committee.
"If the State Department doesn't get the money that they have requested for the transition in Iraq, we are really going to be in the soup," he said.
The remaining U.S. troops in Iraq are scheduled to leave by the end of this year, at the request of the Iraqi government, and the State Department plans to enlarge its role at the Baghdad Embassy and consulates, as well as at police training posts around the country.
The State Department is asking for dramatic increases in equipment, including helicopters and armed vehicles, to keep its personnel safe.
Gates said that after spending as much as $900 billion and losing more than 4,000 American lives, the United States is at the end-game in Iraq.
"If we can't have a transition to the State Department and the police training function, if they don't have a presence in various places throughout Iraq, much of the investments that we have made in trying to get the Iraqis to the place they are is at risk, in my view," Gates said.
Some lawmakers object to the increased role and increased cost of the State Department in Iraq, and there is a growing debate over how to protect these U.S. civilians in coming years.
Gates himself said he would prefer that the U.S. military provide the necessary security for civilians from the State Department and other U.S. agencies, such as the departments of Justice and Agriculture, and police trainers.
Sen. Lindsey Graham, R-South Carolina, said it would take more than $5 billion for the State Department to build up its own security apparatus.
"Do they buy helicopters? Do they buy 54 MRAPS," or mine resistant and ambush protected vehicles, he asked. "And is it wise to hire a private contractor army to replace the American military if the Iraqis will allow the American military to assume that function?
"I have grave concerns about building a State Department army."