Shares of major U.S. airlines traded lower on Friday. At the time of writing, United Airlines (UAL.US) fell more than 7%, while Delta Air Lines (DAL.US) and American Airlines (AAL.US) each dropped over 5%.

The decline follows reports that the U.S. State Department approved the departure of non-emergency personnel and family members of its diplomatic mission in Israel on the 27th. U.S. Ambassador to Israel Huckabee advised those planning to leave Israel to do so "today." Separately, countries including Canada have recently urged their citizens to depart Iran immediately.

With the arrival of the U.S. Navy's largest aircraft carrier, the USS Gerald R. Ford, in Israel on the 27th, observers suggest the risk of a U.S.-Iran conflict has risen sharply.