US President George W Bush has pledged to do "what it takes" to help the new Iraqi government to succeed.
The new security plan is the toughest since the invasion of 2003
His comments came in a news conference following a surprise trip to Baghdad on Tuesday, where he met new Prime Minister Nouri Maliki.
"I saw first-hand the strength of his character and his deep determination to succeed," Mr Bush told reporters.
He also announced details of tough new measures in Baghdad in an effort to win back control of the city's streets.
Some 40,000 Iraqi and US troops were put on the streets just after dawn as part of a crackdown ordered by Mr Maliki.
He has said he is willing to talk to some insurgents, as long as they do not have blood on their hands.
Meanwhile violence continued, with clashes breaking out between gunmen and security forces in the city's north.
40,000 troops on the streets, extra checkpoints, more night raids and air strikes
Ban on personal weapons
Overnight curfew extended to begin at 2030
Vehicle ban during Friday afternoon prayers
Special uniforms and badges for all security personnel
Hotline for anonymous tip-offs
No casualties were reported in the clashes, in the mainly Sunni Adhamiya district, which officials said lasted about half an hour.
A car bomb also exploded in northern Baghdad, killing at least two people and injuring 10, police said. A second car bomb exploded in another northern area, but no-one died.
Fears are high that al-Qaeda in Iraq is preparing new attacks after the killing of their leader Abu Musab al-Zarqawi.
Zarqawi's successor, named as Abu Hamza al-Mujahid, has reportedly vowed to defeat "crusaders and Shias" in Iraq.
Mr Bush acknowledged that violence in Iraq would never be completely eliminated.
But he said intelligence gathered from raids after the death of Zarqawi was being used to track down insurgents.
"I was inspired to be able to visit the capital of a free and democratic Iraq," Mr Bush said of his visit on Tuesday, which gave Mr Maliki just five minutes' warning.
The US president had been chairing talks in the US on future policy in Iraq and had been due to speak to Mr Maliki via videophone.
He said the trip had banished any doubts about the new government's "will to go forward".
Mr Bush described the new prime minister's agenda and cabinet as "impressive".
"I came away with the feeling they're plenty capable people," he said.
The new security measures will be the strictest imposed on Baghdad since the US-led invasion in 2003.
On Wednesday, the nightly evening curfew began at 2030, not 2300 as it did before, and will run until 0600.
Extra troops were posted throughout Baghdad in the morning, setting up new checkpoints to secure road travel in and around the city.
Residents said they had already noticed the difference, with more vehicles being stopped and searched and long queues building up as a result.
But the BBC's Hugh Sykes in Baghdad says checkpoints and patrols provide easy targets for car bombers, and ordering a suicide car bomber to pull over could prompt him to detonate, thereby helping him to achieve his objective.
Insurgents are to be targeted by snap raids, with the majority of resources deployed to the most dangerous areas of Baghdad.
But the question among Iraqis is whether this is just a show of force or whether it can make a dent in the daily bombings and shootings that claim at least 20 to 30 lives in the capital every day.