May 27 (Reuters) - Military drones straying into the airspace of Finland, Estonia, Latvia and Lithuania are stoking concerns that the war in Ukraine is spilling over into NATO's northern borders with Russia.
As Ukraine steps up long-range attacks on Russian Baltic Sea oil shipping ports, some of its drones have missed their targets and led to security warnings in neighbouring countries. In the case of Latvia, it led to a government collapse.
Following is a timeline of recent drone incidents involving
Finland and the three Baltic states:
March 25 - Two stray Ukrainian military drones enter Estonia and Latvia via Russia. One hits a chimney at Estonia's Auvere power station, near the Russian border, and another crash-lands in Latvia.
Lithuania had earlier reported a Ukrainian drone crashing into a lake.
March 29-30 - Finland reports a suspected territorial violation by unmanned aerial vehicles in its southeast and deploys F/A-18 fighter jets. One flying object is identified as a Ukrainian AN-196 drone.
Finnish Prime Minister Petteri Orpo says strong Russian electronic jamming could explain drones drifting into Finnish airspace.
March 31 - Estonia and Latvia detect foreign drone activity near their borders with Russia, and the Finnish border guard finds a drone on its territory. Estonia later discovers drone debris in Tartu County.
April 1 - Estonia's armed forces say drones detected in the country appear to have come from Ukraine and to have been intended for Russia.
May 7 - Latvia and Lithuania call on NATO to strengthen air defences after two suspected stray drones cross from Russia and crash in Latvia. One explodes at an oil storage facility in the Latvian region of Rezekne, damaging four empty oil tanks.
May 10 - Andris Spruds resigns as Latvia's defence minister after Prime Minister Evika Silina says anti-drone systems had not been deployed fast enough. Ukraine says the drones were Ukrainian but had been diverted by Russian electronic warfare.
May 14 - Silina resigns as prime minister, triggering the collapse of Latvia's coalition government after Spruds' Progressives party withdraws support.
May 15 - Finnish authorities warn 1.8 million people in the wider Helsinki region to stay indoors because of suspected drone activity, and suspend air traffic at the capital airport while scrambling fighter jets.
President Alexander Stubb says there is no direct military threat to Finland.
May 17-18 - Explosives are found near the debris of a suspected Ukrainian military drone that crashed in Lithuania, near the Latvian border and Belarus. Lithuanian officials say the drone was not detected when it entered the country.
May 19 - A Romanian NATO fighter jet shoots down a suspected Ukrainian drone over Estonia after it enters Estonian airspace from Russia.
Ukraine apologises to Estonia and other Baltic allies saying Russia redirected the drone through electronic warfare, and denies using Latvian or Estonian territory to launch strikes on Russia.
May 20 - Lithuania issues an "air danger warning", tells people in Vilnius to take shelter and suspends traffic at the capital's airport over a drone in its airspace.
Lithuanian lawmakers seek refuge underground at parliament, while train traffic is suspended and schools and kindergartens are told to take children to shelters.
The government says the drone's origin has not been confirmed.
May 21 - Latvia's armed forces say that at least one drone is flying in the country's airspace and that NATO fighter jets are seeking to combat the threat, and that people in regions bordering Russia and Belarus should take shelter.
(Reporting by Jesus Calero, Editing by Terje Solsvik and Timothy Heritage)
