– President Obama said Friday that he would make a decision “in the days ahead” about whether to use U.S. military power to help the besieged Iraqi government stave off collapse at the hands of Islamist insurgents, but he ruled out using ground forces.

As the president spoke in Washington, Iraq’s top Shiite cleric appealed to all able-bodied Iraqis to take up arms to combat the marauding Sunni extremist militants who have seized broad stretches of the country this week and are threatening the wobbly Shiite-led central government in Baghdad. Obama said it was up to the Iraqis themselves to contain the crisis.

The call to arms by the cleric, Grand Ayatollah Ali al-Husseini al-Sistani, was the most urgent sign yet of the growing desperation of the country’s Shiite majority in the face of a resurgent Sunni militant movement drawn from the insurgency in neighboring Syria and vestiges of the Saddam Hussein loyalists toppled from power by the U.S.-led invasion a decade ago.

Al-Sistani’s plea came as both the United States and Iran, adversaries on a range of issues including the Syria conflict, were both seeking ways to help the government of Prime Minister Nouri al-Maliki and avoid a collapse in Iraq that would further destabilize the Middle East.

At the same time, the ayatollah’s plea also risked plunging Iraq further into the pattern of sectarian bloodletting between Sunnis and Shiites that convulsed the country during the height of the U.S. occupation.

For the United States, the chaos engulfing Iraq risks re-entangling the U.S. military in a conflict the Obama administration spent its first term winding down. Obama said it was clear that al-Maliki’s government needed more help and that the United States was weighing a range of options. But Obama said he would not be sending troops back and U.S. military aid alone was not a solution.

“The United States is not simply going to involve itself in a military action in the absence of a political plan by the Iraqis that gives us some assurance that they’re prepared to work together,” he said. “We’re not going to allow ourselves to be dragged back into a situation in which, while we’re there, we’re keeping a lid on things” while the political leaders fail to address the underlying fissures dividing Iraqi society.

“We will not be sending U.S. troops back into combat in Iraq, but I have asked my national security team to prepare a range of other options,” he said. The president said planning would take “several days” to make sure any airstrikes were effective.

“People should not anticipate that this is something that is going to happen overnight,” he said. “We want to make sure that we have good eyes on the situation there. We want to make sure that we’ve gathered all the intelligence that’s necessary so that if in fact I do direct and order any actions there, that they’re targeted, they’re precise and they’re going to have an effect.”

Obama emphasized that the problem was not just a short-term threat to the Iraqi government but also a long-term failure by Baghdad leaders to achieve political reconciliation across sectarian lines. He warned Iraqi leaders that if they want U.S. help, they have to come up with a plan to accommodate minority factions in a meaningful way.

CNN reported that the Pentagon was moving an aircraft carrier, the USS George H.W. Bush, to the area. Secretary of State John Kerry said that he expects “timely decisions from the president regarding the challenge.”

While Obama ruled out reinserting ground troops, even airstrikes would represent a significant turnaround for a president who was elected in part because of his opposition to the Iraq war and who, after he took office, made pulling out U.S. troops his top foreign policy priority.

Thousands of Iraqi Shiites responded to the call by al-Sistani, 83, whose statements carry enormous weight among not just the Shiite majority but members of other groups including some Sunnis. The statement, read by his representative during Friday prayers, said it was “the legal and national responsibility of whoever can hold a weapon to hold it to defend the country, the citizens and the holy sites.”

Volunteers to fill the gaps

The representative of al-Sistani, Sheikh Abdul Mehdi al-Karbalaie, said volunteers “must fill the gaps within the security forces,” but cautioned that they should not do any more than that.

The statement stopped short of calling for a general armed response to the incursion led by the Islamic State of Iraq and Syria (ISIS), a Sunni extremist group that has emerged as one of the most potent opposition forces in the Syrian civil war and that now controls large areas of both Syria and northern Iraq.

The sheik emphasized that all Iraqis should join the fight, pulling together, so the country does not slide into all-out sectarian warfare. But in a time of mounting frictions and deepening distrust between the sects, it appeared unlikely that many Sunnis would answer the ayatollah’s call. Many Sunnis feel little sympathy either for the government or for the extremists of ISIS.

Volunteers began to appear at the southern gate to Baghdad, which leads to the predominantly Shiite south of the country, within an hour after al-Karbalaie broadcast al-Sistani’s call.

At the police post there, by the soaring arches that mark the city limits, a pickup truck driven by elders pulled up with six young men in the back.

“We heard Ali Sistani’s call for jihad, so we’re coming here to fight the terrorism everywhere, not just in Iraq,” said Ali Mohsin Alwan al-Amiri, one of the elders.

The Sunni insurgents continued their offensive Friday, fanning out to the east of the Tigris River, and at least temporarily seized two towns near the Iranian border, Sadiyah and Jalawla. Security officials in Baghdad said government troops, backed by Kurdish forces, counterattacked several hours later and forced the insurgents to withdraw, a rare success.

In its language and tone, al-Sistani’s statement portrayed it as a religious and patriotic act to volunteer either for the Iraqi army or for a Shiite militia, two forces that are becoming difficult to distinguish.

Cheers greet cleric’s call

When al-Karbalaie said, “Whoever can hold a weapon has to volunteer to join the security forces,” the call was greeted with cheers and shouts of “It will be done!”

People in al-Sistani’s office said the statement was a response to one issued by the leadership of ISIS threatening to seize not just the predominantly Sunni areas of northern Iraq, but also Baghdad and the cities of Karbala and Najaf, which are sacred to Shiite Muslims.

“Iraq and the Iraqi people are facing great danger,” al-Karbalaie said. “The terrorists are not aiming to control just several provinces. They said clearly they are targeting all other provinces including Baghdad, Karbala and Najaf.

“So the responsibility to face them and fight them is the responsibility of all, not one sect or one party. The responsibility now is saving Iraq, saving our country, saving the holy places of Iraq,” al-Karbalaie said.

Since the insurgents captured Mosul, Iraq’s second-largest city, senior officers in the army have been meeting with local committees and Shiite militias in Baghdad and asking them to round up volunteers to bolster the government forces.

Maj. Gen. Abdul Jabbar, commander of the 11th Division, went to a stadium in the Hussainiya neighborhood to speak to a gathering of local sheiks, and called on each of them to produce 50 volunteers.