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President Obama urged Iraq's leaders Friday to "solve their problems" as they face Al Qaeda-inspired militants overrunning cities and marching toward Baghdad -- but said he was reviewing possible U.S. military responses.

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Obama, speaking on the South Lawn before departing for North Dakota, reiterated that the U.S. would "not be sending U.S. troops back into combat."

He said the unrest in Iraq, though, poses a "danger" to the Iraqi people and could threaten American interests.

Indicating a decision on possible U.S. intervention could still be days away, the president said he's asked his security team for options and is reviewing them.

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    Obama made clear, however, that any U.S. involvement likely would be limited, pressing the embattled Iraqi government to develop a "political plan" and make a "sincere effort" to resolve sectarian divisions.

    "We can't do it for them," Obama said.

    The message echoed that delivered earlier in the day by Secretary of State John Kerry, who put the onus on the Nouri al-Maliki government to "put sectarian differences aside and to come together in unity to begin to be more representative and inclusive."

    Republican lawmakers and military analysts are urging the administration to get more involved -- Obama appeared to open the door Thursday to the possibility of air strikes, but no decision has been made. Kerry said Friday the U.S. has "discussed a range of options including military action to provide support for the Iraqi government." He predicted "timely decisions" from the president.

    Meanwhile, the Sunni militants continue their march through northern cities and towns, toppling fragile security forces and threatening to lay siege to the capital city of Baghdad.

    Congressional Republicans say the Maliki government is far from blameless here, having stoked sectarian tensions by alienating the Sunni minority -- in turn fueling the insurgency -- but say U.S. intervention is needed.

    "The Iraqi government is far from perfect," Rep. Ed Royce, chairman of the House Foreign Affairs Committee, R-Calif., said. "But if we don't want to see an Iraq with large swaths of territory under militant control, and we shouldn't, we should answer Iraqi requests to target these Al Qaeda terrorists with drone strikes."

    Heavily armed ISIS forces (The Islamic State of Iraq and the Levant/Syria) pushed Friday into a province northeast of Baghdad, capturing two towns there after having already toppled cities in the country¹s north.

    Police officials said ISIS forces driving machine gun-mounted pickups entered two towns in Diyala province late Thursday -- Jalula, 80 miles northeast of Baghdad, and Sadiyah, 60 miles north of the Iraqi capital.

    Iraqi soldiers abandoned their posts there without any resistance, the officials told The Associated Press.

    There were reports that the main highway from the north to Baghdad was strewn with the decapitated bodies of government security forces, and that ISIS forces were driving and displaying captured armored vehicles.

    The fresh gains come as Maliki's Shiite-led government struggles to form a coherent response after the Sunni militants blitzed and captured the country's second-largest city of Mosul as well as other, smaller communities and military and police bases.

    The new offensive by the militant group is the biggest threat to Iraq's stability since the U.S. withdrawal at the end of 2011, and it has pushed the nation closer to a precipice that would partition it into Sunni, Shiite and Kurdish zones.

    Trumpeting their victory, the militants declared they would impose Shariah law in Mosul, Iraq's second-largest city they captured on Tuesday, and other areas they seized, and promised to march on Baghdad, joined by Saddam Hussein-era loyalists and other disaffected Sunnis.

    In northern Iraq, Kurdish security forces moved to fill the power vacuum caused by the retreating Iraqi forces, taking over an air base and other posts abandoned by the military in the ethnically mixed city of Kirkuk.

    The Obama administration is still struggling to put together an appropriate response to the crisis -- but insisted it does not want U.S. troops in the middle of the fight.

    "We are not contemplating ground troops," White House Press Secretary Jay Carney said Thursday.

    President Obama promised Thursday to send more military aid, without saying what kind of new assistance would be given to Baghdad. Two U.S. officials who are familiar with ongoing negotiations told The Associated Press the White House is considering air strikes and increased surveillance, requested this week by the Iraqi defense minister, as the insurgency nears Baghdad.

    According to the White House, Vice President Biden spoke Thursday with Maliki and expressed "solidarity" with the Iraqi government in its fight against the Islamic State of Iraq and Syria.

    Meanwhile, three planeloads of Americans -- mostly contractors and civilians -- were in the process of being evacuated Friday from an Iraqi air base north of Baghdad, the Associated Press reported. The State Department said Thursday that the U.S. Embassy in Baghdad is operating as usual.

    The development signals the worsening security environment in the northern part of the country. One senior official told Fox News that the focus for evacuation at this point is on people outside of Baghdad.

    Two senior intelligence sources, though, told Fox News there is serious concern about how to evacuate other Americans out of Iraq if the situation further deteriorates.

    "We need places to land, we need safe and secure airfields," one source said, noting that the militants are "seizing airfields and they have surface-to-air missiles, which very clearly threatens our pilots and planes if we do go into evacuation mode."

    Sources said "all western diplomats in Iraq are in trouble," and American allies are scrambling to put together an evacuation plan. Military officials said there are "not a lot of good options."

    Baghdad authorities, meanwhile, tightened security and residents stocked up on essentials. Hundreds of young men crowded in front of the main army recruiting center in Baghdad after authorities urged Iraqis to help battle the insurgents.

    Security officials said ISIS fighters had control of two weapons depots holding 400,000 items, including AK-47 rifles, rockets and rocket-propelled grenades, artillery shells and mortars.

    The U.N. Security Council met on the crisis, underscoring the growing international alarm over the stunning advances by the Islamic State.

    The Iraqi government has been asking for more than a year for surveillance and armed drones to combat a Sunni insurgency that has gained strength from battlefield successes in neighboring Syria.

    Republican lawmakers were harshly critical Thursday of the Obama administration's response. Sen. John McCain, R-Ariz., called for Obama to replace his national security team.

    House Speaker John Boehner snapped: "What's the president doing? Taking a nap."

    Obama commented on the violence shortly afterward.

    "What we've seen over the last couple of days indicates the degree to which Iraq is going to need more help," Obama said. "It's going to need more help from us, and it's going to need more help from the international community."

    In addition to the possible military assistance, the U.S. is sending about $12 million in humanitarian aid to help nearly a million Iraqis who have been forced from their homes by recent fighting in the nation's north and west.

    Fox News' Justin Fishel and Adam Housley and The Associated Press contributed to this report.