"We don't need to talk to anyone else," he said.
A U.S. diplomat said that growing frustration over the Americans' failure to rein in the security firms had transformed Sunday's shooting into a symbol of abuses committed over the years by the more than 20,000 foreign security guards that supplement U.S.-led military forces in Iraq.
"It's amazing the Iraqi government did it, but they did it because we wouldn't," the diplomat said, referring to the temporary revocation of Blackwater's license.
U.S. officials said that although Prime Minister Nouri Maliki and other officials had spoken angrily about the shooting, the consultations between the governments had been calm.
"Iraq has sovereignty, but its sovereignty at the moment is imperfect because it hasn't replaced the laws that have preceded the [Coalition Provisional Authority] documents," one Western advisor to the Iraqi government said on condition of anonymity because of the topic's sensitivity.
Asked whether the U.S. government would hand over an American citizen to Iraqi authorities for questioning, State Department spokesman Sean McCormack said in Washington that it would depend on the results of a U.S. investigation.
"You get into issues of diplomatic immunity here," McCormack said. "It may come back to this answer of, well, it depends on the individual and their particular status."
U.S. government officials and security industry executives have argued that there are sufficient U.S. laws to prosecute misdeeds by overseas contractors in American courts.
In a rare April interview with a website dedicated to contractor issues, Blackwater President Gary Jackson said that several U.S. laws, particularly the Military Extraterritorial Jurisdiction Act, or MEJA, already gave American prosecutors the right to go after private citizens operating in war zones.
"I can't put it any more simply: We don't need a new law, we need to enforce the ones we have," Jackson said. "Blackwater has always supported increased enforcement of these existing laws."
Such prosecutions have been rare. There is also a lack of agreement on whether MEJA applies to Blackwater because the group works for the State Department, not the Pentagon.
In February, David A. Passaro, hired by the CIA as a contractor, was convicted of assaulting an Afghan terrorism suspect who later died. Sentenced to eight years and four months in prison, Passaro remains the only contractor convicted of such abuses in Iraq or Afghanistan.
McCormack said the U.S. would share results of its investigation of the shootings with Iraqi authorities, and said the Iraqi government was examining its laws to see whether any were applicable.
"To boil it down very simply, there are a lot of cross-cutting jurisdictional as well as legal authorities here, and you would have to have a precise set of facts in order to be able to determine the various applicable legal authorities and whether or not there were any laws that were broken," he said.
A joint U.S.-Iraqi military investigation of Sunday's incident has also been launched, the Western advisor to the Iraqi government said.
In other developments Tuesday, two car bombs and a roadside explosion killed 15 people in east Baghdad. The deadliest attack was a car bombing in the parking lot of the Health Ministry and Baghdad's main hospital complex, killing seven people and wounding 23, police said.
Times staff writers Paul Richter and Peter Spiegel in Washington and Said Rifai, Raheem Salman and special correspondent Usama Redha in Baghdad contributed to this report.