Displaced Iraqis from the Yazidi community settle outside a camp near the Syria-Iraq border, in Iraq on Saturday.
The United States is studying possibilities to help the civilians trapped on a mountain in northern Iraq by the advance of Sunni militants -- including possible humanitarian corridors or air lifts.
US President Barack Obama has pledged to help save the tens of thousands of members of minority groups, mainly Yazidis, stranded on Mount Sinjar, threatened by militants from the Islamic State (IS) jihadist group and a worsening humanitarian situation.
"There are a range of options. I don't want to get ahead of decisions that haven't been made yet. We're going to rely on what the teams report back in terms of their assessment," Deputy National Security Advisor Ben Rhodes said Wednesday.
"But you look at corridors, you look at airlifts.... That's exactly what our team is doing on the ground now in Iraq," he explained.
On Tuesday, Defense Secretary Chuck Hagel announced the deployment of 130 additional military advisors to Arbil, the capital of capital of the autonomous Kurdish region in northern Iraq, to give a "more in-depth assessment" of how to help the trapped Iraqis.
Rhodes added Obama was going to make a decision "in a matter of days."
"We don't believe it's sustainable to just have, you know, permanent air drops to this population on the mountain," he said, referring to the repeated deliveries of food and drinking water dropped by US aircraft this past week.
Rhodes said the United States was coordinating with Kurdish forces as well as with international partners.
Meanwhile, the Pentagon confirmed that four V-22 Osprey aircraft had arrived in Arbil along with the 130 military advisors, but refused to say whether they could be used to evacuate civilians.
On Tuesday, United Nations human rights experts in a message to the international community, called for urgent action to block a "potential genocide" on Mount Sinjar.
The IS militants launched an offensive on June 9, swiftly taking over the main northern city of Mosul before sweeping across much of the Sunni heartland.