Iraq crisis: No quick fix, Barack Obama warns
US President Barack Obama has warned it is "going to take some time" to help Iraqis overcome the jihadist-led Sunni rebellion and stabilise their country.
It would be a "long-term project" to revamp and resupply the military and build support among Sunnis, he said.
Mr Obama stressed that progress would depend on Iraqis coming together and forming an inclusive government.
The Islamic State (IS), formerly known as Isis, has seized swathes of northern and western Iraq in recent months.
Mr Obama said air strikes on Friday - the first time US forces have been directly involved in a military operation in Iraq since they withdrew from the country in late 2011 - had destroyed IS arms and equipment.
They had also prevented attacks by the al-Qaeda breakaway on thousands of members of the Yazidi religious minority group stranded on a mountain in the north-west, the president added.
The Yazidis fled to Mount Sinjar a week ago after IS fighters overran a nearby town where many had been sheltering over the past two months.
Earlier, the UK said it had sent a cargo plane to help with the relief operation that has seen US aircraft drop thousands of bottles of water and ration packs in the area over the past two days.
One C-17 and two C-130 transporters dropped 72 bundles of supplies, according to the Pentagon. They were escorted by F/A-18 Hornet jets launched from the USS George H W Bush aircraft carrier in the Gulf.
"We feel confident we can prevent [IS] from going up the mountain and slaughtering the people who are there," Mr Obama said.
"But the next step, which is going to be complicated logistically, is how do we give safe passage for people down from the mountain and where can we ultimately relocate them so that they are safe."
France would begin deliveries of first aid equipment to Iraq in the next few hours, President Francois Hollande's office announced.
IS fighters meanwhile began hoisting their black flags at the Mosul dam, Iraq's largest, and patrolling its perimeter, days after seizing the facility.
Mr Obama said a long-term strategy was needed to confront the jihadists.
He would not give a timetable for US military involvement, saying it would depend on Iraq's religious, ethnic and political groups forming an inclusive government.
"I don't think we are going to solve this problem in weeks,'' he said. "I think this is going to take some time."
"The Iraqi security forces - in order to mount an offensive and be able to operate effectively with the support of populations in Sunni areas - are going to have to revamp and get resupplied and have a clear strategy. That is all going to be dependent on a government that the Iraqi people and the Iraqi military can have confidence in."
Iraq's politicians have been unable to form a government since April's parliamentary elections, which were won by Prime Minister Nouri Maliki's State of Law Coalition.
He has rejected calls to step down from Sunnis, Kurds and some fellow Shia, who accuse him of mishandling the security crisis and pursuing sectarian and authoritarian policies during his two terms in office.
Mr Obama said the gains made by IS and its allies since June had been "more rapid than expected" in intelligence estimates and that it had provided a "wake-up call for a lot of Iraqis inside Baghdad".
He added that he would not be closing the US embassy in Baghdad or the consulate in Irbil, the capital of the semi-autonomous Kurdistan Region, and that he had an obligation as commander-in-chief to protect the US diplomats and military personnel stationed there.
But he also reiterated that US combat troops would not be returning to Iraq.
"We are going to maintain that because we should have learned a lesson from our long and immensely costly incursion into Iraq."
- The majority are Chaldeans, part of the Catholic Church
- Numbers have fallen from around 1.5 million since the US-led invasion in 2003 to 350,000-450,000
- In Nineveh province, they live mainly in towns such as Qaraqosh (also known as Baghdida), Bartella, al-Hamdaniya and Tel Kef
- Secretive group whose origins and ethnicity are subject to continuing debate
- Religion incorporates elements of many faiths, including Zoroastrianism
- Many Muslims and other groups view Yazidis as devil worshippers
- There are estimated to be around 500,000 Yazidis worldwide, most living in Iraq's Nineveh plains