Iraq's government announced Tuesday that its military had launched a counterattack aimed at driving the Islamic State terror group out of the western part of Anbar province just days after militants captured the city of Ramadi.

Iraqi state TV announced the start of the operation, which was backed by Sunni and Shiite paramilitary forces, but did not provide further details. The possibility of a large-scale counteroffensive has sparked fears of potential sectarian violence in the Sunni province, long the scene of protests and criticism against the Shiite-led government in Baghdad.

Still, senior U.S. defense officials at the Pentagon pushed back on the reports Tuesday morning that the counterattack had begun. Two sources described the actions as "shaping operations" -- or battlefield preparations -- at this stage.

Pentagon spokesman Col. Steve Warren said this includes airstrikes, and artillery and rocket barrages. "We welcome the news" of the counter-offensive, he said.

A spokesman for Iraq's Shiite militias said the operation will "not last for a long time" and that Iraqi forces have surrounded the provincial capital, Ramadi, from three sides. Ahmed al-Assadi, who is also a member of parliament, told reporters that new weapons are being used in the battle "that will surprise the enemy."

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The announcement of the attack came hours after U.S. Vice President Joe Biden spoke to Iraqi Prime Minister Haider al-Abadi in an effort to smooth over comments made Sunday by Defense Secretary Ash Carter in which he accused Iraqi forces of showing "no will to fight" in Ramadi.

A White House statement on Monday describing Biden's call said the vice president welcomed an Iraqi decision to mobilize additional troops and "prepare for counterattack operations." Biden also pledged full U.S. support to "these and other Iraqi efforts to liberate territory from ISIL," the statement said, using an acronym for Islamic State, which is commonly known as ISIS.

Saad al-Hadithi, a spokesman for al-Abadi, had said Monday his government was surprised by Carter's comments.

"We should not judge the whole army based on one incident," al-Hadithi told The Associated Press.

Al-Hadithi said the Iraqi government believes the fall of Ramadi was due to mismanagement and poor planning by some senior military commanders in charge. However, he did not elaborate, and no action has been taken against those commanders.

The fall of Ramadi marked a major defeat for Iraqi forces, which had been making steady progress against the extremists over the past year with the help of U.S.-led airstrikes.
Security forces and Sunni militiamen who had been battling the extremists in Ramadi for months collapsed as IS fighters overran the city. The militants gained not only new territory 70 miles west of Baghdad, but also large stocks of weapons abandoned by the government forces as they fled.

Meanwhile, Iranian Gen. Qassim Soleimani was quoted in an Iranian daily newspaper as saying that the U.S. didn't do a "damn thing" to stop the ISIS advance on Ramadi, adding that Iran and its allies are the only forces that can deal with the threat.

"Today, there is nobody in confrontation with (ISIS) except the Islamic Republic of Iran, as well as nations who are next to Iran or supported by Iran," he said.

Fox News' Lucas Tomlinson and The Associated Press contributed to this report.