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The U.S. carried out an airstrike near Baghdad on Monday as the beginning of intensified action against ISIS militants in Iraq, defense officials told NBC News.

U.S. attack aircraft hit an ISIS fighting position southwest of the capital in support of the Iraqi security forces, defense officials said. There was also at least one airstrike near Mount Sinjar in northwestern Iraq, the officials said.

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U.S. Central Command later confirmed the airstrikes, saying the airstrike southwest of Baghdad was the first the U.S. has undertaken as part of expanded efforts to "degrade and ultimately destroy" ISIS that President Barack Obama outlined in an address last week. Six ISIS vehicles near Sinjar and an ISIS fighting position southwest of Baghdad that was firing on Iraqi personnel were destroyed, Central Command said.

In Iraq, the earlier airstrikes were mainly to protect important sites, like Mosul Dam and the city of Erbil, or to break the seize on Mount Sinjar, where thousands of religious minorities had been trapped by the militants.

The airstrike Monday near Baghdad was more offensive in nature and was not triggered by any advance of ISIS toward the Iraqi capital, a defense official said.

Secretary of State John Kerry joined leaders from more than 20 countries at a strategy meeting Monday in Paris. Some countries, notably Turkey, have been hesitant to pledge help, but the U.S. insists it will have all the firepower it needs.

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— Courtney Kube, Erin McClam and M. Alex Johnson