The measures come after President Putin announced a “special military operation” in the Donbass region.
Russia announced the closure of its airspace to civil flights on the western border with Ukraine and Belarus, while Ukraine closed its airspace to civil flights and the European aviation regulator also put warns of the dangers of flying in the border areas of Russia and Belarus.
The measures taken on Thursday came after Russian President Vladimir Putin announced a special military operation in the Donbass region.
“The use of airspace on Russia’s western border with Ukraine and Belarus has been temporarily suspended due to the high threat to the safety of civilian aircraft flights after the use of weapons and of military equipment,” a Notice to Airmen or Notice to Air Missions (NOTAM) said.
In a separate statement on Thursday, Russia’s Defense Ministry said it was using “high-precision weapons” to disable air defense systems, military airports and the air force in Ukraine.
Ukraine’s State Air Traffic Services Enterprise said on its website that the country’s airspace was closed to civilian flights from 00:45 GMT on Thursday, with air traffic services suspended.
The European Union Aviation Safety Agency (EASA) said airspace in Russia and Belarus within 100 nautical miles of their borders with Ukraine could also pose safety risks.
“In particular, there is a risk of both intentional targeting and misidentification of civilian aircraft,” the agency said in a conflict zone bulletin.
“The presence and possible use of a wide range of ground and airborne warfare systems presents a high risk to civilian flights operating at all altitudes and flight levels.”
The aviation industry has become more aware of the risks that conflict poses to civil aviation since Malaysia Airlines flight MH17 was shot down over eastern Ukraine in 2014.
EASA said the Russian Defense Ministry sent an urgent message to Ukraine warning of a high risk to flight safety, due to the use of weapons and military equipment from 00:45 GMT, and asked Ukrainian air traffic control to stop the flights.
On Thursday, President Vladimir Putin authorized “a special military operation” against Ukraine to eliminate what he said was a serious threat, saying he was aiming to demilitarize Russia’s southern neighbour.
In a morning address on state television, Putin said he had no choice but to launch the operation, the scope of which was not immediately clear but appeared to go well beyond the assistance to Russian-backed separatists in eastern Ukraine.
“I decided to carry out a special military operation,” Putin said, sitting at a Kremlin desk next to a battery of phones, the Russian flag behind him.
“Its purpose is to protect people who have been victims of intimidation and genocide… over the past eight years. And for this we will fight for the demilitarization and denazification of Ukraine.
“And to bring to justice those who have committed numerous bloody crimes against civilians, including against citizens of the Russian Federation.”
Ukraine dismisses as fabricated Russian charges of genocide against people living in parts of its east seized by Russian-backed separatists in 2014.
Kiev said Putin was looking for an artificial pretext to attack him.