article_snippet.sent: The reinforcements come four days after ISIS began attacking northern Iraq's Baiji oil refinery, a key strategic resource that has long been a target because the facility refines much of the fuel used by Iraqis domestically.
article_snippet.sent: ISIS launched an assault on the Baiji oil refinery late Saturday.
article_snippet.sent: By Sunday, ISIS said ISIS fighters were inside the Baiji oil refinery and controlled several buildings, but Iraqi government security officials denied that claim and insisted that Iraqi forces remained in full control.
article_snippet.sent: the media office of the Hasd Al-Shaabi militia said Tuesday that Iraqi troops already at the Baiji oil refinery were holding Iraqi troops ground, preparing to push ISIS out of the facility entirely.
article_snippet.sent: The attack could have a significant effect if The attack damages oil fields or machinery.
article_snippet.sent: the Baiji oil refinery is 40 kilometers (25 miles) from Tikrit.
highlights_snippet.sent: ISIS attacked the Baiji oil refinery Saturday .
  
highlights_snippet.sent: The refinery, Iraq's largest, has long been a lucrative target for militants .