Jamie Freed, Tim Hepher

(Reuters) – Ukraine announced on Thursday that it has closed its airspace for civilian flights due to a “high danger” to safety. Europe’s aviation regulator warned of the risks of flying into Russia or Belarus bordering countries because of military activity.

Russian President Vladimir Putin approved a military operation to liberate eastern Ukraine, Thursday. This was believed to mark the beginning of European war.

Ukraine State Air Traffic Services Enterprise announced on its website, that civil flights had been halted in Ukraine’s airspace starting at 0045 GMT (Thursday) and that all air traffic services were suspended.

According to the European Union Aviation Safety Agency, (EASA), airspace within Russia and Belarus that is less than 100 nautical miles (185km) from their border with Ukraine can pose safety hazards for airlines.

The agency issued a conflict bulletin stating that “In particular there is a chance of both intentional targeting or misidentification civil aircraft.”

The possibility of civil flight operations at any altitude or level is subject to high risks due to the presence and potential use of various ground and aerial warfare systems.

After Malaysia Airlines Flight MH17 was downed over eastern Ukraine, in 2014 the aviation industry became more concerned about conflicts.

EASA stated that Russia’s Ministry of Defence has sent an urgent message warning Ukraine of the high danger to safety of flight due to use of weapons, military equipment and other means of communication. It asked Ukraine to immediately stop all flights.

According to flight tracking sites, early morning traffic was seen in the country’s north and west corridors.

Flight tracking site FlightRadar24 reports that an El Al plane flying from Tel Aviv, Israel to Toronto suddenly made a U-turn to avoid Ukraine’s aviation. This happened around the time Ukraine was closing.

A LOT Polish Airlines flight connecting Warsaw with Kyiv also returned to Warsaw about the same period.

Safe Airspace (which was created to offer safety and conflict zone info after the downings of MH17) stated hours earlier that its risk level had increased over Ukraine. They advised people to “do NOT fly”.

It warned about the possible cyberattack on Ukraine’s air traffic control.

A notice to pilots stated that Russia had also closed part of Rostov’s airspace east of Ukraine’s border to ensure safety for civil aviation.

The restrictions on airspace were not known to Ukraine before the United States, Canada, France, Italy and Britain advised their airlines that they should avoid airspace over Crimea and eastern Ukraine. However, this was not a complete ban.

Lufthansa, Germany’s national airline, has canceled flights to Ukraine starting Monday. KLM had already cancelled flights.

Last week, two Ukrainian airlines reported problems with securing travel insurance. Meanwhile foreign carriers started to avoid the country’s airspace after Russia gathered a large military force at its borders.