The top U.S. general is resisting giving a timetable for withdrawal from Iraq, telling Congress that progress there remains "fragile."
General David Petraeus told the Senate Armed Services Committee in Washington on Tuesday that by July, the United States should withdraw the extra combat troops sent last year as part of the "surge" to reduce violence.
But he said commanders should then evaluate the security situation for 45 days before deciding when more troops could come home.
Petraeus and the U.S. Ambassador to Iraq, Ryan Crocker, are testifying in front of congressional committees today and Wednesday.
They said after five years of war, Iraq's security has improved. But they said that gain, and fragile economic and political progress, could be reversed.
Both men accused Iran of backing militias that continue to jeopardize Iraq's stability.
Crocker also warned that seriously changing America's current engagement in Iraq would bring failure.