IRBIL, Iraq — An Iraqi general said Saturday that Baghdad was secure, as hundreds of Iraqis converged on volunteer centers across the capital in response to a call by Iraq’s highest Shiite cleric to fight back against a Sunni jihadist group making rapid gains across the north.

Maj. Gen. Qassim al-Moussawi, speaking on behalf of the armed forces, told reporters in Baghdad that the city was “stable” and that the military was coordinating with forces in Samarra and other areas north of the capital to retake territory claimed by the insurgents.

“Our security forces have regained the initiative to launch qualitative operations on various fronts over the past three days and have achieved remarkable victories with the help of volunteers,” Moussawi said. Iraqi security forces claimed Saturday to have regained control of the small town of Ishaqi, north of Baghdad.

Moussawi’s comments came as Defense Secretary Chuck Hagel ordered a U.S. aircraft carrier into the Persian Gulf, in a move a Pentagon spokesman said was intended to give President Obama “additional flexibility should military options be required to protect American lives, citizens and interests in Iraq.”

The USS George H.W. Bush was expected to arrive in the Gulf from the Arabian Sea by Saturday night, along with a guided-missile cruiser USS Philippine Sea and guided-missile destroyer USS Truxtun, Pentagon press secretary Rear Adm. John Kirby said.

Iran’s president, Hassan Rouhani, meanwhile, said that his country was prepared to step in to help Iraq but that Iraqi authorities had not yet requested assistance.

“We are ready to help Iraq within the framework of international law, and if the Iraqi government and nation ask us to do so, we will consider it,” Rouhani told reporters in Tehran.

Rouhani would not confirm or deny reports that the Quds Force, an elite unit of Iran’s Revolutionary Guard Corps, had entered Iraq to assist Prime Minister Nouri al-Maliki’s government. But Iran’s interior minister, Abdolreza Rahmani Fazli, said that the country has “no intention of sending military forces to Iraq.”

“Instead we’ll provide consultation and guidance to Iraqi forces,” Fazli said in Tehran, according to the semiofficial Mehr News Agency. “But if terrorists get close to our borders, we will destroy them.”

Both sides in the conflict claimed Saturday to have inflicted large numbers of casualties. The Islamic State of Iraq and Syria said on its official Twitter account that it had executed 1,700 Shiite soldiers Friday. Meanwhile the pro-government Iraqia satellite channel reported that Iraqi forces had killed nearly 300 “terrorists” across northern Iraq on Saturday. It was impossible to verify the numbers from either side.

In Baghdad, Iraqi Shiite volunteers gathered in response to a call to arms by Ayatollah Ali Sistani, who Friday had urged the nation’s Shiites to fight back against the al-Qaida-inspired ISIS, setting the stage for sectarian war.

The satellite channel Sky News Arabia broadcast footage showing dozens of Iraqis gathering at centers in Baghdad to sign up.

Shiite religious volunteers would partially plug the ranks of Iraq’s decimated security forces, after jihadists from ISIS seized ground in an area from the northern city of Mosul to a town just 60 miles north of Baghdad this past week in a stunning military advance that threatens to divide the fragile nation.

Iraqi government forces, aided by Shiite militias, clashed Saturday with “Iraqi revolutionaries” and “armed insurgents from ISIS” in the city of Muqdadiyah, 60 miles northeast of Baghdad, which resulted in the withdrawal of Iraqi army and police from the city, the Saudi satellite network al-Arabiya reported. But a tribal leader from the town told Reuters later that Iraqi security forces had regained control.

Local media also reported Saturday that Iraqi airstrikes had killed people in the towns of Tikrit, Jalawla and Saadiyah, which ISIS seized in recent days.

A spokesman for the Iraqi air force said that the air force had carried out multiple strikes in several parts of northern Iraq, killing 100 ISIS militants, Sky News Arabia reported.

Maliki and his administration have appeared to exaggerate the armed forces’ capabilities, despite growing evidence that Iraqi soldiers abandoned their weapons and fled almost as soon as they were confronted by ISIS forces last week.

The mobilization of Shiite volunteers signaled an additional dark turn for a nation that saw tens of thousands of its citizens die in sectarian violence that erupted during the U.S. occupation between 2003 and 2011.

The developments also appeared directly at odds with the approach urged by Obama, who appealed to the Iraqi government Friday to find ways to bridge the country’s sectarian divisions.

Kuwaiti media reported Saturday that Iraqi militiamen were also gathering along Iraq’s southern border to secure the predominantly Shiite city of Basra, which is also home to some of Iraq’s most important oil reserves.

The new recruits will face militants who have received a significant military boost from warehouses of equipment left behind by the retreating Iraqi army.

Hisham al-Hashemi, an Iraqi security analyst who claimed to be privy to Defense Ministry estimates, gave a glimpse of how devastating the losses to the Iraqi army may have been. He said the rout has cost the army equipment worth $1.3 billion, including 72 tanks – much of it hardware supplied by the United States.

Maliki, himself a Shiite, has long been accused by both Shiite and Sunni opponents of stirring divisions between the Muslim sects to cling to power.

On Saturday, al-Arabiya claimed that Maliki was threatening to shut down the Saudi network’s office in Baghdad. Saudi Arabia’s monarchy has harbored a long-standing animosity toward Maliki, and al-Arabiya’s coverage of the Iraq crisis has displayed hints of glee over the Sunni insurgents’ gains.

On Friday, Maliki chose to address the nation from the city of Samarra, north of Baghdad, where Iraq’s worst period of sectarian bloodshed kicked off with the bombing of a sacred Shiite shrine in 2006.

Maliki called the symbolic city, which is also the hometown of the jihadists’ commander, Abu Bakr al-Baghdadi, “a launchpad” for the fight against ISIS, Reuters reported. From Samarra, Maliki insisted that the country is “not sectarian” and “will fight as a nation.”

He said Iraqi forces needed to act quickly to defeat the jihadists. “We need to do it within hours,” he said according to the Al Jazeera English satellite channel. “Because this is our country and we cannot feel safe without beating them.”

Iraqi state television showed recruits who will be used to protect sites such as the Samarra shrine – where ISIS forces attempted an assault this week – scrambling to board packed army trucks.

The Iraqi security forces, on which the United States has spent billions for arms and training, are “increasingly going to become another Shiite militia in all but name,” fighting alongside other Shiite militias and the Iranians, according to Kenneth Pollack of the Washington-based Brookings Institution.

“This is the start of the Iraqi civil war that was so obviously going to break out after we washed our hands of it,” he said.