A senior defense official said Wednesday that Iraqi leaders are hoping to present Iranian officials with the latest evidence that Iran is giving weapons and training support to militias in Iraq.

The official spoke on condition of anonymity because of the sensitivity of the information.

Defense Secretary Robert Gates, who is meeting with Mexican leaders, has said that the meeting does not represent the U.S. laying the groundwork for an attack against Iran. And his spokesman Geoff Morrell told reporters Wednesday that he is not aware of any "ramping up or revision" of war plans for Iran at the Pentagon.

It is not known yet whether the Iranians agreed to the meeting. But the official said the Iraqis want to try to let Iran know that the support is not helpful and should be stopped.

U.S. Death Toll Sets New Mark

The killings of three U.S. soldiers in separate attacks in Baghdad overnight pushed the American death toll for April up to 47, making it the deadliest month since September, the military said Wednesday.

The news comes the day before the fifth anniversary of President George W. Bush declaring major combat operations over in Iraq. He made the statement from the deck of an aircraft carrier off the coast of California.

One soldier died when his vehicle was struck by a roadside bomb. The other died of wounds sustained when he was attacked by small-arms fire, the military said. Both incidents occurred Tuesday in northwestern Baghdad.

A third soldier died in a roadside bombing Tuesday night in the east of the capital, the military said.

The statement did not give a more specific location. But the eastern half of Baghdad includes embattled Sadr City and other neighborhoods that have been the focus of intense combat between Shiite militants and U.S.-Iraqi troops for more than a month.

In all, at least 4,059 members of the U.S. military have died since the Iraq war started in March 2003, according to an Associated Press count.

Crackdown Leader's Nephew Hangs

Iraq's prime minister said that a relative of an Iraqi government official has been killed and hung from a pole in Sadr City.

Tuesday's slaying was in apparent retaliation for the spokesman's role in Iraq's crackdown against Shiite militias, Nouri al-Maliki said.

The attack on the nephew of the Interior Ministry spokesman took place in the Baghdad neighborhood that's a stronghold of Shiite cleric Muqtada al-Sadr and his Mahdi Army militia.

The uncle was in charge of the crackdown on the Mahdi Army that began in Basra in late March. The uncle has survived other assassination attempts.

Al-Malaki vowed to continue cracking down on militias, which he said stand in the way of a united Iraqi army.

Clashes in Sadr City today have left 12 militants dead.

Gates Praises Crackdown

Gates said the situation in Baghdad represents a conflict between the Iraqi government and "lawless elements that do not want to be part of the political process."

"I think everyone has made clear that if the Sadrists are willing to participate in the political process, that they would be welcome in that process," Gates said, adding that he believed the effort is helping unify the Iraqi government.

"What is intriguing is that, because of the way the prime minister has taken on (the Mahdi Army militia) and special groups in Basra and some of these other gangs, the rest of the Iraqi government that has not exactly been known for its unity has, in fact, unified behind Prime Minister Maliki," Gates said. "He has gotten the vocal support of virtually all elements of the government, and partly because they see him acting against a sectarian group that they were concerned he wouldn't act against."

Among Iraq's neighbors, "at least all but one have taken positive notice," as well, Gates said, in a reference to Iran.