The U.S. Federal Aviation Administration has been declaring a lot of no-fly zones lately.
On Wednesday, the FAA extended a ban on U.S. airlines flying to and from Israel's Ben Gurion International Airport for up to 24 hours. The FAA initiated the ban on Tuesday, after a rocket struck about a mile from the airport. The strike had come amid renewed violence between Israel and Hamas in Gaza that claimed hundreds of lives in the past week.
Last week the FAA declared an indefinite prohibition on all U.S. flight operations in eastern Ukraine, after a Malaysia Airlines flight was shot down on Thursday, killing all 298 passengers.
All FAA declarations of no-fly zones or restricted airspaces are known as Notices to Airmen (NOTAMS). Many of those notices are for North Africa and the Middle East, where unrest in recent years has spurred a series of new restrictions.
Other restrictions are long-standing. The Democratic Republic of the Congo, for instance, has been the subject of an FAA Notice to Airmen advising pilots to maintain an altitude of 15,000 feet above the country since 2002. The advisory, which aims to keep flights out of ground-based-weapons range, came after a civilian Boeing 727 was shot down by a ground missile.