BAGHDAD, Iraq (CNN) -

The chairman of the U.S. Joint Chiefs of Staff, Gen. Martin Dempsey, left the door open Thursday to stepped-up U.S. military involvement in Iraq if ISIS militants pose a threat to the United States.

In response to a question about what the U.S. end game is in Iraq, Dempsey began by saying the U.S. military's current role is much different from it was during the Iraq war.

"Assessing and advising and enabling are very different words than attacking, defeating and disrupting," he said during a briefing at the Pentagon in Washington. "We may get to that point if our national interests drive us there, if (the Islamic State in Iraq and Syria) becomes such a threat to the homeland that the President of the United States, with our advice, decides that we have to take direct action. I am just suggesting to you that we are not there yet."

Dempsey also disputed the use of the term "mission creep" in Iraq.

"That's the wrong phrase. The issue is mission match," he said.

"We will match the resources we apply with the authorities and responsibilities that go with them based on the mission we undertake, and that is to be determined."

Barzani: It's time for referendum on independence

Masoud Barzani, the President of Iraq's semiautonomous Kurdish region, told the regional parliament Thursday that it is time to hold a referendum on the independence of Kurdish areas.

He said Kurds should no longer have to wait on anybody to obtain the right of independence and told the Kurdish parliament to begin taking steps to hold the referendum.

Last week, Barzani announced that disputed areas, including Kirkuk, were henceforth part of the Kurdish autonomous region, after the Iraqi central government failed to hold a long-awaited referendum.

Last month, the Iraqi army withdrew from Kirkuk, and Kurdish Peshmerga forces took control of the city and small villages in the areas as ISIS carried out its lightning offensive.

The move by the Kurds will probably complicate efforts to get Iraqi lawmakers to form a new government representing all three major population groups -- Sunnis, Shiites and Kurds.

Official: Nuns, orphans missing

Two nuns, who were thought to be under house arrest by ISIS militants, and three orphans have gone missing from an Assyrian Orthodox church in central Mosul, the governor of Nineveh province and witnesses told CNN on Thursday.

Militants believed to be from the Islamic State in Iraq and Syria initially barred the nuns from leaving Miskintah Church in the Khazraj neighborhood in early June, Gov. Atheel al-Nujaifi said.

The two nuns manage an orphanage on the church grounds, and both are very well known to Mosul residents, the residents say.

Residents in the neighborhood who were in touch with the nuns told CNN they had not been able to reach them on their cell phones since Tuesday. On Thursday, the residents forced their way into the church and said they could not find the nuns or three orphans.

The two nuns were identified by the governor and the residents as Sister Hannah and Sister Uttor.

Indian nurses being moved

Forty-six Indian nurses being held by ISIS in former Iraqi leader Saddam Hussein's hometown of Tikrit are being moved north, to the city of Mosul, which is under control of the militant group, Syed Akbaruddin, the spokesman for India's Ministry of External Affairs, said Thursday at a news briefing.

The news about the nurses follows reports that Iraqi security forces have been battling ISIS militants for control of the city, north of Baghdad, raising questions about whether ISIS is losing its grip on the area.

Syed said his understanding is that the nurses have been moved for their own safety.

"All of them are safe and unharmed," he said.

Asked whether the nurses were being held against their will, he said: "In zones of conflict, there's no free will."

Turkish truck drivers released

Thirty-two Turkish truck drivers who went missing in early June in Mosul, when ISIS fighters swept through the city, have been released, Turkish Foreign Minister Ahmet Davutoglu said Thursday in a televised news conference carried by Turkish television stations.

"As a result of efforts and daily consultations for the past 23 days, now I am happy to say that our 32 drivers have been received by our consul general, and now our consul general is on the way to Irbil with the drivers," Davutoglu said.

The drivers will then be flown to Ankara, Turkey, he said.

There are still more than 40 staff members of the Turkish Consulate missing in Iraq, Davutoglu said. Efforts continue "nonstop" for their safe return, he said.

Among those missing are special forces soldiers, diplomats and children, who were seized by ISIS militants on June 11.

Baghdad bombings

A double bombing in Baghdad's predominantly Shiite neighborhood of al-Furhat left eight people dead and 17 wounded, police officials said early Thursday.

The blasts late Wednesday night targeted people leaving the al-Mustafa mosque after evening prayers in the neighborhood, which sits just 2 miles from Baghdad International Airport, the officials said.

More than 16 people have been arrested in connection with the attack, officials said.

They did not say whether those arrested were believed to be militants tied to ISIS.

Fighting in Karbala

Dozens were reportedly killed in days of fighting between Iraqi security forces and followers of a prominent Shiite cleric in the holy city of Karbala, south of Baghdad, authorities said Thursday.

The fighting raises concerns about whether infighting could fracture Iraq's Shiite majority, potentially sparking further violence in a country already battling extremist Sunni militants.

The battle began Tuesday when Iraqi troops raided the offices of prominent Shiite cleric Mahmoud al-Hassani al-Sarkhi, sparking a battle with the cleric's followers, they said.

The raid came after the cleric's followers blocked roads in and around shrines in Karbala.

Al-Sarkhi has been a fierce critic of Prime Minister Nuri al-Maliki and the United States.

Last week, he blamed some of the bloodshed on the country's top Shiite cleric, Ayatollah Ali al-Sistani, who called for Iraqis to take up arms against ISIS extremists.

Helicopters fired a number of times on the Saif Saad neighborhood, not far from the city's famed holy shrines, on Tuesday night, an employee at a shrine and a resident of Karbala said. The aircraft again hovered over the area Wednesday, as the city was placed on high alert and the streets remained empty of civilians.

Videos posted on YouTube purported to show a firefight between Iraqi forces and the cleric's followers, including one that showed an Iraq Humvee burning as gunfire is heard in the distance.

CNN cannot confirm the authenticity of the videos.

Fighting in Diyala, Salaheddin provinces

Iraqi security forces, with the help of volunteer fighters and Sunni tribesmen, were carrying out an offensive Thursday against ISIS fighters north of Baquba in Diyala province, security officials told CNN on Thursday.

The towns of al-Dawaleeb and al-Shohani, about 35 kilometers (22 miles) north of Baghdad, have been cleared of militants, the officials said.

They said a number of ISIS fighters were killed and wounded during the operation, which lasted 7 hours.

The officials say a large number of bombs were planted in both towns by ISIS, and Iraqi forces were working to defuse them.

Meanwhile, state-run Iraqi TV reported that a counterterrorism unit killed 88 extremists and destroyed 12 vehicles in Salaheddin province Thursday. It offered no evidence of the killings, and no further details were provided.

CNN cannot independently confirm the claims.