The number of US troops killed in hostile action in Iraq since President George W Bush declared major combat over has exceeded those killed during the war itself.
The president declared an end to major hostilities on 1 May
The number of post-war deaths rose to 115 following the killing of two soldiers north of Baghdad. The Pentagon says 114 US soldiers were killed by hostile fire during the war.
US officials said the latest victims were soldiers of the 4th Infantry Division, who died when an explosive device was detonated as their convoy passed by.
The BBC's Jonny Dymond in Baghdad says attacks against US forces have ebbed and flowed since major hostilities officially ended on 1 May, but every week has brought some fatalities.
Our correspondent says the deaths of US and British troops receive much publicity, but Iraqis have been killed in far greater numbers.
He says there are no official figures for how many Iraqis are killed every day.
However, one assessment based on the number of bodies coming into Baghdad's morgue suggests that just over 1,500 deaths are attributable to the breakdown in law and order since the fall of the old regime.
Bush compared suicide bombings in Iraq to the 11 September attacks
Some observers say the violence is deliberately timed to coincide with the start of the holy Muslim month of Ramadan.
At least 35 people died and more than 200 were injured on Monday in Baghdad when suicide bombers attacked three Iraqi police stations and the headquarters of the International Committee of the Red Cross.
On Tuesday, President Bush said the United States would not be intimidated by those trying to create a "climate of fear" in Iraq.
The president drew a parallel between the suicide bombings in Iraq and the 11 September, 2001, attacks in the United States.
"It's the same mentality," Mr Bush said. "We'll just destroy innocent life and watch the United States and their friends and allies, you know, crater in the face of hardship."
A suspected bomber captured in a foiled raid during the Monday blasts in Baghdad was a Yemeni national with a Syrian passport, US military sources said.
US death toll in Iraq
115 deaths in combat
116 in hostile incidents since 1 May, when major operations in Iraq declared over
79 US deaths in 1991 Gulf War
Mr Bush told reporters the US had made it clear to Syria and Iran that they must stop fighters crossing into Iraq.
The BBC's security correspondent Frank Gardner says intelligence experts believe also Osama Bin Laden's al-Qaeda network could have been involved.
President Bush said the US was "constantly looking at the enemy" and adjusting its response accordingly.
He said the US would set up more blockades and inspections and seek to give Iraqis a bigger role in intelligence-gathering to thwart attacks.
Analysts said Mr Bush's words appeared intended to address criticism that the White House had failed to anticipate rising violence in Iraq and was uncertain about how to deal with it and protect American lives.