BAGHDAD, Iraq (CNN) -- A senior U.S. military official say 400 U.S. military personnel are being sent to Basra, Iraq, to bolster the operation there.
Within 24 hours of the latest round of fighting in Basra, the U.S. began moving dozens of military personnel to the city as Iraqi forces were becoming overwhelmed, CNN has confirmed with the senior military official. The move included senior American officers.
Many of the details first appeared in Thursday's New York Times.
Meanwhile, a U.S. airstrike "against enemy forces" in Basra killed two people and destroyed a house, the U.S. military said Thursday.
U.S. forces launched the overnight airstrike on the western Basra neighborhood of Qibla after troops "were attacked with small-arms fire by two criminals on a rooftop," the military said.
"The ground force called in supporting aircraft to engage the individuals. An F/A-18 carried out a precision airstrike on the house, and coalition forces on site confirmed that two [enemies] were killed in the airstrike," the military said.
News reports said civilians were killed. The military said it is "looking into the matter." It is also investigating reports that civilians were killed in a second airstrike.
The Basra strike supported the Iraqi-led offensive that began last week, targeting criminal elements in the southern Iraqi city. The troops are targeting strongholds of Shiite militants, including members of cleric Muqtada al-Sadr's Mehdi Army, which has a strong presence in Qibla.
Al-Sadr's political wing is asking Iraqis to peacefully protest the U.S. presence in Iraq on Wednesday, the anniversary of the 2003 fall of Baghdad. Two top U.S. officials in Iraq are scheduled to testify before Congress next week as well.
Hundreds were killed and wounded in recent fighting across Iraq's Shiite regions, which ended when al-Sadr ordered his militia to stand down this week after talks with Iranian and Iraqi Shiite officials.
The United States and Britain have supplied air support during the campaign in Basra, called Operation Charge of the Knights. The U.S. military said Thursday that Iraq's fledgling air force also has been involved in the operation.
That force has "planned, executed and monitored 104 missions in support of Iraqi ground forces in Basra between March 25 and April 1."
Despite sporadic clashes, a relative peace is returning to Basra, police said. Watch how life seems to be returning to normal »
Military and political officials hope to end the offensive soon, and Prime Minister Nuri al-Maliki, who had been in Basra, has returned to Baghdad, declaring the operation a success. Defense and Interior Ministry officials remain in Basra to guide security force actions.
The Basra operation has stoked Shiites' rage, and the violence has spread across southern Iraq into Baghdad.
It aggravated fighting among Shiites, particularly clashes between the Mehdi Army and the Badr Organization, a group affiliated with the Islamic Supreme Council of Iraq that has a strong presence in security forces.
The U.S. and British militaries have backed up Iraqi security forces but have not participated in ground operations. However, the discord was significant enough for Britain to announce that it was delaying the withdrawal of 1,500 troops.
As the Basra operation continued Thursday, al-Sadr's movement urged Sunnis, Shiites, Kurds, Arabs, "mujahedeen and the patient people" to converge on Najaf on Wednesday.
The group is urging Iraqis to wave flags, demand Iraqi independence, support Iraqi unity, support "oppressed people" -- and do so in a way that dignifies Islam.
"It is the time to express your rejection and raise your voices loudly in Iraq's sky against the unjust occupier, the enemy of nations and humanity, and against the awful massacres committed by the occupier and unjust people against our noble nation," a Sadrist statement said.
Al-Sadr sponsored a similar demonstration last year that attracted thousands of participants.
Also next week, Gen. David Petraeus, the top U.S. general in Iraq, and U.S. Ambassador to Iraq Ryan Crocker are set to testify Tuesday before Congress about U.S. troop strength in Iraq. They are also expected to pass along recommendations for U.S. efforts there.
• A U.S. airman was killed Thursday by an improvised explosive device while on patrol in central Baghdad, the military said. The name of the airman, who was assigned to Multi-National Division-Baghdad, was withheld pending notification of relatives. The death brings to 4,013 the number of U.S. service members who have died since the Iraq war began in March 2003.
• Iraq may be more contaminated with unexploded ordnance than any other nation, according to a U.N. report. Live cluster bombs, landmines and other munitions put Iraqis at risk, especially children who play with the explosives, the report said. There have been 565 casualties resulting from the detonation of unexploded devices since 2006. A quarter of those were children, the report said.
• At least one Iraqi was killed and 10 others wounded when a car bomb detonated near a police patrol in western Baghdad's Harthiya neighborhood in the Mansour district, an Interior Ministry official said Thursday. Police and civilians were among the casualties. An earlier bombing in Mansour wounded a police officer, the official said.
• A roadside bomb targeting an Iraqi army patrol killed at least one soldier and wounded another in western Baghdad's Yarmouk district Thursday, an Interior Ministry official said.
• Coalition troops east of Samarra killed four men in fighting that erupted Wednesday after soldiers stopped a truck containing a suspected insurgent, the U.S. military said. U.S. and Iraqi soldiers have been stepping up their fight in northern Iraq against al Qaeda in Iraq, a largely Sunni insurgent group.
• In Baghdad's predominantly Shiite Sadr City neighborhood, at least three people were killed and 13 others, including a local TV cameraman, were wounded Wednesday by a roadside bomb, an Interior Ministry official said. E-mail to a friend
CNN's Jomana Karadsheh and Mohammed Tawfeeq contributed to this report.