(CNN) -- The United States launched a series of airstrikes Wednesday against ISIS forces in Iraq, the same day President Barack Obama vowed to act against the militant group following its beheading of an American journalist and its threat to kill another. "The United States of America will continue to do what we must do to protect our people. We will be vigilant and we will be relentless," the President said in televised remarks. Obama vowed justice for James Foley, calling his killing by ISIS, which refers to itself as the Islamic State, an act of violence that "shocked the conscience of the entire world."
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NEW: United States attempted a rescue in Syria, Pentagon spokesman says
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More Americans, including Steven Sotloff, held by ISIS, official says
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"The United States will do what we must," President Obama says
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Airstrikes resume near Mosul Dam, a day after video of U.S. journalist
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The President's statement followed Tuesday's release by ISIS of a video that showed Foley's killing and carried a stark warning that a second @placeholder, believed to be journalist Steven Sotloff, would be killed, if the United States did not end its military operations in Iraq.
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The President's statement followed Tuesday's release by ISIS of a video that showed Foley's killing and carried a stark warning that a second American, believed to be journalist @placeholder, would be killed, if the United States did not end its military operations in Iraq.
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Whether @placeholder lives or dies, the executioner said on the video, depends on what Obama does next.
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Another @placeholder official, speaking on condition of anonymity, told CNN that the mission was to rescue Foley and others being held at an undisclosed location.