The situation in Iraq continues to intensify with an attack made by Islamic militants on Iraq's largest oil refinery late Tuesday might. The strategic move in the the militant lightning attack threatens the country's domestic oil supply. 

Just 155 miles north of Baghdad, the al-Queda-inspired militants fought with fire and mortar shells into Wednesday morning, the security official said. 

READ MORE: U.S. Special Forces Might Send Troops To Iraq 

"The oil refinery in Beiji has been under siege since the militant fighters of ISIS seized the town of Beiji in their sweep through northern Iraq," said NPR's Deborah Amos, reporting from Irbil, Iraq. "In an offensive at dawn, ISIS fighters attacked the refinery with machine-gun fire and mortars, according to Iraqi security forces."

The Iraqi government is currently using limited air attacks to strike back at ISIS, the self-named Islamic State of Iraq and Syria, which now controls large parts of northern Iraq.

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