Timothy Garton Ash, historian, journalist, and lecturer at Oxford and Stanford Universities, shared his opinions in an interview with Espreso TV."I think Russia is pursuing two goals. The first, as you rightly say, is to destroy Ukraine as an independent state and recover its basically hegemony over Eastern Europe to try to demilitarize, to roll back everything that has been done since 1991. The other is, of course, and it's connected, for Russia to be recognized again as a great power, a superpower. So one is to restore the Russian Empire, and the other is for Russia to be recognized, above all by the United States, as a great power. So that's the maximum objectives for Russia," Ash explained.The historian noted that Russia has already started a hybrid war against Europe. He added that Putin only understands the language of force and that Russian military targets in NATO airspace need to be shot down."I think, again, you have to distinguish between the United States under Donald Trump and Europe. For Europe, I think there is clearly a red line, which is an attack on NATO territory. Now, the problem is, how do you define an attack on NATO territory? We've had Russian fighter planes over Estonia, i.e. NATO airspace for 12 minutes. We've had assassinations. We’ve had arson attacks. We’ve had cyber attacks. We've had major acts of disinformation. All of these are actions of hybrid war. So the challenge for Europe is to define where that red line exactly is when, yes, this is an attack on NATO and therefore on Europe. My view is we should make it totally clear that the next time a Russian fighter jet enters NATO airspace anywhere in Europe for more than 30 seconds, it will be shot down, which is what Turkey did five years ago. That's the only way in which you can get this kind of message through to someone like Vladimir Putin," he added.After meeting with Ukrainian leader Volodymyr Zelenskyy in New York, U.S. President Donald Trump said that NATO countries should shoot down Russian aircraft that fly into their airspace.On the night of Friday, September 26, Denmark again closed its airspace due to reports of suspicious objects in the sky. Two flights were canceled on the morning of September 26.