White House officials on Tuesday confirmed the death of an American reported to have been fighting for the
"We were aware of U.S. Citizen Douglas McAuthur McCain's presence in Syria and can confirm his death," said a statement released by Caitlin Hayden, a spokeswoman for the National Security Council.
"We continue to use every tool we possess to disrupt and dissuade individuals from traveling abroad for violent jihad and to track and engage those who return."
State Department officials earlier had declined to confirm that McCain was fighting for the Islamic State at the time of his death.
"We are in contact with the family and are providing all possible consular assistance," said spokeswoman Jen Psaki. "Out of respect for the family we're not going to be adding any more comment at this time."
When a U.S. citizen is killed overseas, American consular officials often help the family locate and return the citizen's body to the United States, if possible.
NBC reported that McCain, 33, was one of three foreign fighters aligned with Islamic State forces killed in a battle in Syria.
After growing up in Minnesota, McCain moved to San Diego and attended San Diego City College. College officials confirmed his attendance but declined to provide additional details.
On a Facebook page identified as belonging to McCain, he referred to himself as Duale ThaslaveofAllah. The Facebook page has since been taken down.
On a Twitter account identified as belonging to McCain, he used the name Duale Khalid and wrote, "It's Islam over everything."
The person said he converted to Islam a decade ago: "I will never look back the best thing that ever happen to me," reads one Twitter message.
The Twitter messages display hostility toward gays, white people and Somali immigrants in San Diego. The messages praise Allah and smoking hookah.
One tweet reads: "It's funny to me how all these so call Muslim claim that they love Allah but always curse the one who try to implement his laws."
A retweet from a group called Islamic Freedom reads: "Allah never promised this life was easy, but He did promise that He would be with you every step of the way."
The Twitter account includes a translation of a speech by Islamic State spokesman Abu Muhammad Al-Adnani.