There are "nearly a dozen" Americans fighting for the militant group the Islamic State in Iraq and Syria (ISIS), The New York Times reports, based on statements from U.S. officials. 

The Thursday report follows news this week that at least one American, Douglas McAuthur McCain, had been killed in Syria while fighting for ISIS. 

There have been fears over Americans and others with Western passports getting training and experience in Syria and returning to the U.S. House Intelligence Committee Chairman Mike RogersMichael (Mike) Dennis RogersOvernight Cybersecurity: DHS chief delivers warning to cyber attackers | Tech giants pledge not to help government cyberattacks | Justices toss DOJ case against Microsoft Former senior government officials come out in support of Pompeo Overnight Cybersecurity: Highlights from Zuckerberg, round two | Senate panel to consider bill protecting Mueller | Pentagon could roll out cyber posture by August MORE (R-Mich.) said on "Meet the Press" on Sunday that “they are one plane ticket away from U.S. shores, and that’s why we’re so concerned about it.“

Separately, the United Nations said late Thursday that 43 United Nations peacekeepers had been captured by Syrian rebels in the Golan Heights. 

The U.N. said the peacekeepers were captured by "Security Council-designated terrorist groups and by members of non-State armed groups." 

The Security Council condemned the capture. Its member countries "called upon countries with influence to strongly convey to the armed members of the opposition in the area of operation to immediately release the peacekeepers," the council said in a statement.