Iraq must take more responsibility on security and political issues, a senior White House adviser has said.
Iraq's deputy PM said more units were being trained
Dan Bartlett said that Baghdad needed to "take a step forward on very difficult issues".
He said "benchmarks and milestones" would be used to track Iraq's progress, but these were not linked to deadlines or threats to withdraw troops.
The remarks follow growing calls from senior officials and politicians for US and British troops to be withdrawn.
Mr Bartlett also said that White House thinking had never been properly described by the phrase "stay the course".
"What we aren't doing is sitting there with our heads in the sand," he said.
"It is important that the Iraqi government take a step forward on very difficult issues, both on the security front and on the political front," he said.
He told Fox News the US strategy must be to press Iraq to take more responsibility but to do so in a way that did not weaken the new government.
The comments echoed those made recently by James Baker, the co-chair of a commission charged with reviewing the government's Iraq policy.
He said that Washington needed to chart a policy between "stay the course" and "cut and run".
The BBC's Justin Webb in Washington says the problem the White House faces is that politicians across both major parties have lost patience with the government of Iraqi Prime Minister Nouri Maliki.
Senior Democrat Senator Joe Biden said that Washington needed to issue an ultimatum to Mr Maliki.
"We should tell them straight up now: 'Get a political settlement or you're on your own, Jack,'" he said.
Wayne White, a former deputy director of Iraq intelligence in the US State Department, told the BBC that pressure was mounting for a major change in approach - "either withdrawal or a major shift in strategy".
In London, Iraqi Deputy Prime Minister, Barham Saleh, said his government would "assume more and more responsibility in the security area".
"Today we are 300,000 strong in the police and in the military," he said after a meeting with British Prime Minister Tony Blair.
"They are getting better training and we are establishing more units, and we hope by the end of this year half of Iraqi provinces will come under Iraqi command," he said.
Mr Blair said Britain intended "to hold its nerve" in Iraq, and his office denied he had pressed Mr Saleh for assurances that Iraqi forces could take over policing southern Iraq within a year.
Further violence continued in Iraq on Monday, as the Muslim holy month of Ramadan came to an end:
- Shia militiamen from leading cleric Moqtada Sadr's Mehdi Army dragged four police aligned to the rival Shia Badr Brigades from their houses and killed them in the southern city of Amara, Associated Press reported
- Eight bodies with gunshot wounds to the head, some of the bodies bound, were found in different districts of Baghdad, an Interior Ministry source told Reuters news agency
- A car bomb in an eastern district of Baghdad killed three, AP reported
- The US military announced the death of a marine killed in the western province of Anbar. At least 86 US troops have died this month - the highest monthly toll since November 2004.