Within the past 30 days, a Sunni extremist group has beheaded two American journalists. The group has gone by several names but the most commonly used one in the United States is the Islamic State of Iraq and Syria (ISIS).

Now seen as one of the biggest threats to the United States, the U.S. government is “pursuing a long term strategy against ISIL [ISIS],” U.S. Defense Secretary Chuck Hagel said in a press release Aug. 21.

This came after the release of a video by ISIS showing the beheading of American journalist James Foley. The video was a warning to the U.S. government about their involvement in the Middle East. President Barack Obama did not comply with the warning in the video and increased U.S. efforts against ISIS in the Middle East.

ISIS then created another video showing the execution of American journalist Steven Sotloff despite a plea from Sotloff’s mother directly to the leader of ISIS, Abu Bakr al-Baghdadi.

“They’re beyond just a terrorist group,” Hagel said. “They marry ideology, a sophistication of strategic and tactical military prowess. They are tremendously well-funded. Oh, this is beyond anything that we’ve seen. So we must prepare for everything.”

ISIS has declared an Islamic caliphate in the Middle East. A caliphate is an Islamic state ruled by a single leader known as a caliph. According to British new organisation The Guardian, Baghdadi has called upon all Muslims, not just those in Syria and Iraq, to “swear loyalty to him [Baghdadi].”

Beheading the two journalists is just a sample of ISIS’ many crimes. ISIS has done “ethnic cleansing on a historical scale,” human rights organisation Amnesty International said on their website. “IS [ISIS] has systematically targeted non-Arab and non-Sunni Muslim communities, killing or abducting hundreds, possibly thousands, and forcing more than 830,000 others to flee the areas it has captured since 10 June 2014.”

Obama said in an interview with NBC’s Chuck Todd that he will meet with congressional leaders today and will make a speech about the U.S.’ “game plan” concerning ISIS tomorrow.