WASHINGTON, Shawwal 23, 1435, August 19, 2014, SPA -- U.S. aviation regulators formally barred American carriers from flying through any part of Syrian airspace, citing "extremist groups" involved in hostilities that are "known to be equipped with a variety of antiaircraft weapons which have the capability to threaten civilian aircraft." The announcement replaces previous warnings to U.S. airlines that strongly advised them to avoid flying in that airspace, but gave carriers the option of doing so after advising the FAA. The agency said it based its latest decision on "an updated assessment of the risk" and "the lack of any request from operators wishing to fly in this airspace." According to the FAA's announcement, "the ongoing armed conflict and volatile security environment in Syria poses a serious potential threat to civil aviation." The agency went on to emphasize that "armed extremist groups in Syria" possess antiaircraft weapons and some of them "have successfully shot down Syrian military aircraft" during the conflict in that country. --SPA 12:06 LOCAL TIME 09:06 GMT www.spa.gov.sa/w