The Federal Aviation Administration (FAA) had warned US pilots earlier this year not to fly over portions of Ukraine in the Crimea region, according to notices posted on the agency's website.
The notices were posted on April 23. The UN's International Civil Aviation Organization and the aviation authorities in most countries issue similar notices for areas where unrest or military conflict creates a risk of being shot down.
The FAA had not issued any new warnings today in the immediate aftermath of reports that a Malaysian airliner had been shot down over the Ukraine.
