State Dept.: ISIS is a very serious threat to the homeland

U.S. Officials tell CNN that they knew about Douglas McArthur McCain, a 33-year-old man from Minnesota who died fighting for ISIS - for nearly a decade but missed him when he traveled to the region.

ISIS: Is it really a threat to the U.S.?

A day after news broke about McArthur - a coalition of Syrian opposition groups announced that its forces had killed another American in battle.

The coalition, known as Nahrawan in Syria, released a new video of a deadly battle between ISIS and a coalition of rebel groups. The rebel group claims video shows the battle and the very day McCain was killed.

CNN can't confirm that but we do believe McCain died during this ongoing battle between ISIS and other rebuts.

At the same time, ISIS released video of ISIS fighters firing an American M198 Howitzer cannon.

OutFront, Brett McGurk is the Deputy Assistant Secretary of State for Iraq and Iran.