The United States could end up cooperating with Iran to stop militant gains in Iraq, Secretary of State John Kerry suggested Monday in an interview with Yahoo!News.
But a Pentagon spokesman denied Monday that any military coordination with Iran is in the cards.
In his interview with Yahoo!News, Kerry didn't say that cooperation with Iran is under active discussion inside the administration.
"Let's see what Iran might or might not be willing to do before we start making any pronouncements," he said.
But he went on to say that the he "wouldn't rule out anything that would be constructive to providing real stability."
"I think we are open to any constructive process here that could minimize the violence, hold Iraq together -- the integrity of the country -- and eliminate the presence of outside terrorist forces that are ripping it apart," Kerry said.
His comments are the first time such a high-ranking U.S. official has made such a public statement since militants from the Islamic State in Iraq and Syria began an offensive that has seen vast swaths of northern Iraq fall out of government hands.
Two senior U.S. officials said earlier that the Obama administration is exploring possible direct talks with Iran over the deteriorating situation in Iraq.
Deputy Secretary of State William Burns is in Vienna for nuclear talks with Iran and could hold discussions on the side about Iraq with Iranian Foreign Minister Mohammad Javad Zarif, a senior administration official said in a background briefing with reporters Monday.
But in a signal the administration hasn't yet reached a conclusion about what to do, two administration officials said the United States wasn't interested in teaming up with Iran because the two share few mutual interests.
And Pentagon spokesman Rear Adm. John Kirby told reporters Monday that the Defense Department isn't working on a plan to cooperate with Iran in Iraq.
"There are no plans to consult Iran on military actions inside Iraq," he said. "There is no plan to coordinate military activities."
Iran is an ally of Iraq's Shiite-led government, and a senior security official in Baghdad told CNN on Friday that the country had sent about 500 Revolutionary Guard troops to help fight the ISIS militants.
Iranian President Hassan Rouhani denied the report over the weekend, according to Iranian state television, but said he would be open to helping if asked.
Despite their shared interest in stopping the advance of ISIS fighters in Iraq, the United States is wary of furthering Iran's already considerable influence there.
The Shiite Iranian regime is al-Malaki's closest ally in the region. And the Obama administration is concerned that appearing to team up with Iran would both alienate Iraq's Sunni minority and worry Sunni allies of the United States in the region.
But, as the crisis spreads, officials around the globe are scrambling for any way to slow the militant advance.
ISIS, an al Qaeda splinter group, wants to establish a caliphate, or Islamic state, that would stretch from Iraq into northern Syria. The group has had substantial success in Syria battling President Bashar al-Assad's security forces.
Here's the latest:
Iraq's military strikes back; new images emerge
After days of violent ISIS advances, the Iraqi air force killed more than 200 militants, Iraqi state TV reported Monday. Air raids against ISIS took place in Saqlawiya, northwest of Falluja, according to state TV.
New images emerged Monday purporting to show a militant fighter interrogating and threatening to kill five captives.
And a video appears to show a man in an Iraqi military uniform after he was shot in the face. The fighter boasted on Facebook that he was proud of killing the man and said the video should be passed around to show what could happen to other Shiites.
The new images follow others apparently posted by ISIS to jihadi Internet forums appearing to show the executions of Iraqi security forces and a tweet, on what was claimed to be an ISIS account, saying its members had killed at least 1,700 Shiites.
CNN cannot independently confirm the authenticity of the images or tweets purportedly posted by ISIS.
More militant gains
The militant group racked up several victories across Iraq on Sunday.
The northwestern city of Tal Afar fell to ISIS, according to Iraqi Gen. Mohammed al-Quraishi. Many Tal Afar residents, including ethnic minority Shiite Turkmen, fled the fighting north toward Iraq's Kurdish region.
Also on Sunday, ISIS gained control of two villages in Diyala province, northeast of Baghdad.
And Iraqi security forces and suspected ISIS gunmen clashed near al-Khalis, about 18 miles (29 kilometers) from Diyala's capital of Baquba, al-Khalis police officials told CNN. Three mortar rounds landed near a recruitment center opened recently for volunteers to help the Iraqi army fight ISIS.
ISIS seized Iraq's second-largest city, Mosul, last week and has threatened to march on Baghdad, Iraq's capital and largest city.
Intervention debate continues
Obama's national security
team met through the weekend, discussing the pros and cons of various options.
While U.S. officials have said sending ground troops to Iraq isn't an option, the administration has said it will consider all other options in trying to stem the ISIS advances.
But a U.S. official said last week that even airstrikes, a frequently mentioned option, could prove futile given the lack of credible intelligence and lack of obvious targets presented by ISIS.
The governor of Kirkuk, one of the provinces that has seen heavy fighting, told CNN's Arwa Damon that he would support U.S. airstrikes in Iraq and Syria.
"I don't think anyone is safe from these people," Gov. Najmaldin Karim said.
U.S. sends Marines
An amphibious assault vehicle with 550 Marines aboard was expected to enter the Persian Gulf on Monday, the Defense Department said. The Marines and their V-22 tilt-rotor aircraft could help evacuate Americans from Iraq if necessary, a U.S. defense official said.
Between 50 and 100 U.S. Marines and U.S. Army personnel have already arrived at the U.S. Embassy in Baghdad, a U.S. official told CNN on Sunday.
Some embassy staffers have been moved out of Baghdad, but most remain there, State Department spokeswoman Jen Psaki said Sunday.
Gas prices rise
Even though the ISIS advance hasn't had a major effect on the country's oil exports, gas prices around the world are rising.
Oil experts say the 4% price spike since June 6 -- which has taken a barrel of crude to $107 for the first time since September 2013 -- is being driven by fear that exports could be hit later this year, just as world demand peaks.