The top U.S. military official accused Iran of increasing arms and training support to insurgents in Iraq as well as militants battling U.S. and NATO forces in Afghanistan.
Adm. Mike Mullen, the chairman of the Joint Chiefs of Staff, told a Defense Department news conference that he has "no smoking gun" proof that the highest leadership in the Iranian government has approved the stepped up aid to insurgents who are killing U.S. and Iraqi forces.
But he said it is clear that recently made Iranian weapons are flowing into Iraq at a steadily increasing rate, including to support insurgents during the recent fighting in Basra in southern Iraq.
"It's not just weapons," Mullen said of Iranian support. "They continue to train Iraqis in Iran to come back and fight Americans in the coalition," he added, saying U.S. intelligence is seeing similar Iranian aid for militants and the Taliban in Afghanistan.
"I just don't see any evidence of them backing off. And Basra highlighted a lot of that," Mullen said of Iran.
Still, Mullen added: "I have no smoking gun that could prove the highest (Iranian) leadership is involved in this."
Mullen said the U.S. is not taking any options off the table — including military — to counter the Iranian threat, but he said the Bush administration believes the best approach remains continued diplomacy and discussions with Iran's government, which has said it has been trying to reduce any such support to insurgents across the border in neighboring Iraq.
'Silent victims'The new allegations emerged as the United Nations said insurgent groups and militias in Iraq are recruiting children as suicide bombers.
Echoing concerns expressed recently by the U.S. military, Radhika Coomaraswamy, U.N. special representative of the secretary-general for children and armed conflict, said her recent five-day trip to Iraq convinced her that the country's children are "the silent victims of the ongoing violence."
"Since 2004, an increasing number of children have been recruited into various militias and insurgent groups, including as suicide bombers," said Coomaraswamy in a statement released Friday after she returned to Amman, Jordan. She did not reveal the source of her information.
Children trained to kill?
The U.S. military released several videos at the beginning of February seized from suspected al-Qaida in Iraq hideouts that showed militants training children who appeared as young as 10 to kidnap and kill. The U.S. military said at the time that al-Qaida in Iraq teaches teenage boys how to build car bombs and sends them on suicide missions.
Young children have been used as decoys in Iraq, but they are rarely the ones behind the attacks. Last March, police said children were used in a car bombing in which the driver gained permission to park in a busy shopping area after pointing out that he was leaving his kids in the back seat. The children were killed along with three Iraqi bystanders.
Coomaraswamy urged "religious and community leaders of Iraq to send one clear message to Iraqi children: Stay out of the violence and go back to school."
She said only 50 percent of primary school-age children were attending class, down from 80 percent in 2005. Approximately 1,500 children are known to be held in detention facilities, she added.
The U.N. official called on "all parties to the conflict in Iraq to strictly adhere to international humanitarian standards for the protection of children and to immediately release any children under the age of 18 years who are associated with their forces in any way.
Meanwhile, radical Shiite cleric Muqtada al-Sadr called for an end to clashes between his militia fighters and Iraqi troops, saying that his threat of an "open war" applied only to U.S.-led foreign forces.
In a sermon read by an aide during Friday prayers in Baghdad's militia stronghold of Sadr City, the cleric also urged Iraqi soldiers and policemen "not to support the occupiers in combating your brothers."
Al-Sadr issued a "final warning" to the government Saturday to halt its crackdown against the Mahdi Army or face an "open war until liberation."
The statement on al-Sadr's Web site singled out the Iraqi government led by fellow Shiite Nouri al-Maliki, accusing him of selling out to the Americans. Friday's sermon appeared to be an attempt to ease tensions.
'Stop the bloodshed'
Al-Sadr — who is believed to be in Iran — called on worshippers to remain patient and united.
"If we have threatened with an open war until liberation, we have meant by it a war against the occupier," said the sermon, which was read by the mosque's imam Sheik Hassan al-Edhari.
"I call upon my brothers in police, army and Mahdi army to stop the bloodshed," the sermon said. "We should be one hand in achieving justice, security and in supporting the resistance in all of its forms."
"There will be no war between our Iraqi brothers, whatever their sect or ethnicity," it said.
Military operations launched by al-Maliki late last month in the southern city of Basra led to daily clashes between militia fighters and U.S.-backed Iraqi troops, focused mainly in sprawling Sadr City. Militiamen also fought Iraqi security forces to a virtual standstill last month in Basra before an Iranian-supervised truce.
Years of intense fighting between Shiites and Sunnis had only recently ebbed.
Senior al-Sadr aide Hazim al-Aaraji told The Associated Press that the new message was also intended to be read in Basra but a delegation from the movement was prevented from entering the city. They read it in the southern city of Nasiriyah instead, he said.
"The statement is for all but we aimed for it to be read in Basra and Sadr City because of the violence going on in these two areas," he said. "The aim was to ease the situation in Basra and Sadr City."
The Sadrists accuse al-Maliki, a political rival, of trying to sideline them ahead of expected provincial elections in the fall. They appear divided over whether to launch a full-scale fight against U.S.-led forces or focus on political efforts.
A decision by al-Sadr to lift a nearly eight-month cease-fire would jeopardize recent security gains and threaten an increase of attacks against U.S. troops.
On Thursday, al-Maliki vowed that the crackdown on Shiite militias had won broad political support from Sunni, Shiite and Kurdish political parties and would continue.
The U.S. military said American and Iraqi forces killed 10 militants in overnight clashes in northeastern Baghdad. Most were killed by Hellfire missiles launched from Apache helicopter gunships against groups of militants preparing to fire on U.S. and Iraqi forces from different parts of the district, according to a statement.
Local hospital officials, speaking on condition of anonymity because they were not authorized to speak to the media, said seven people, including two women, were killed and 45 others were wounded in the clashes that were centered in the Sadr City district.
Witnesses said the clashes ended in the early hours Friday.
U.S. soldier dies in bombing
The military also said a U.S. soldier was killed in a roadside bombing south of Baghdad.
The attack raised the American death toll in April to 39, the highest rate of death for troops in Iraq since September, when 65 Americans were killed, according to an Associated Press tally.
In all, at least 4,051 members of the U.S. military have died since the Iraq war started in March 2003, the AP tally showed.
Meanwhile, Iraqi police said a radio journalist was killed in a drive-by shooting near Basra.
Adnan al-Asadi, the head of the local al-Nakhil radio station and police have identified the slain journalist as Jassim al-Batat. They say he was killed by gunmen in a speeding car as he left his house in the town of Qurna in his own car on Friday.
Al-Nakhil radio is based in Basra and is run by the Supreme Islamic Iraqi Council — a powerful Shiite group and chief rival of al-Sadr.