Or empty of airliners at least.
Ukraine has closed its airspace to civil flights following its invasion by Russia in the early hours of Thursday (February 24).
The EU aviation watchdog has also warned that flights within Russia and Belarus within 100 miles of the Ukraine border could be risky.
It says there's a danger of targeting or misidentification of civilian aircraft.
Airlines responded immediately.
One El Al flight from Tel Aviv to Toronto made a sudden turn out of Ukraine's airspace.
A LOT Polish Airlines flight from Warsaw to Kyiv turned back at about the same time.
The air travel industry has taken extra care over conflict risks since Malaysia Airlines flight MH17 was downed over eastern Ukraine in 2014.
The organisation Safe Airspace, which was established after that incident, has now issued a "do not fly" warning for the country.
Russia has also closed some of its airspace close to the border, and suspended domestic flights to the area.
Many western countries had already advised their airlines to avoid some parts of the region, but had stopped short of a total ban.
Lufthansa, KLM and others had already suspended flights.
