Two Iraqi refugees in the United States with alleged ties to the Islamic State were arrested Thursday, one in Sacramento, California and another in Houston, Texas, CBS reports. Both are due in court to face federal charges of supporting terrorism.

Investigators said that the suspects, Aws Mohammed Younis Al-Jayab and Omar Farak Saeed Al Hardan, travelled to the Syrian city of Aleppo to fight alongside the Islamic State terror organization in the civil war. Both suspects are Palestinian-born Iraqi refugees.

The arrests again bring up the debate of bringing Syrian refugees into the United States. CBS law enforcement sources say that these arrests expose security issues that they have been concerned about for quite some time.

"Al Hardan had been in the U.S. since 2009 while Al-Jayab arrived in October of 2012. According to court documents in 2012, 23-year old Al-Jayab used social media to communicate with people inside Syria and expressed interest in his desire to return to Syria to ‘work.' He was also allegedly communicating with 24-year old Al Hardan, who prosecutors say is associated with members and sympathisers of ISIS," CBS reporter Jeff Pegues said.

Al-Jayab lived in Arizona and Wisconsin and spent time at a shooting range, pleaded for travel funds, and asked online friends about how he could get to Syria. By March 2013, he planned to get to Syria by traveling to Turkey and then made his way to Aleppo. In April 2013, he messaged that "he was eager to see blood."

Al-Jayab was aware of U.S. surveillance and knew that his travel to Aleppo, Syria would warrant a charge, and he returned to U.S. in January 2014. He told immigration that he was visiting his grandmother in Turkey.

After the story leaked, Texas Governor Greg Abbott released a statement saying that the arrests were precisely why he called for a halt of refugees entering the U.S. from countries "substantially controlled by terrorists."

According to the U.S. attorney, there is no indication that Al-Jayab planned any terrorist attacks in the U.S.