A security expert said Russia’s violation of Poland’s airspace with drones should be seen a sign for NATO to strengthen its Eastern defence.

Dr Jamie Shea, Professor of Strategy and Security at University of Exeter, told the Associated Press that Russian President Vladimir Putin is a "great risk taker" who has recently attempted to challenge NATO's defences.

"It's only a matter of time before you have one of these missiles or drones landing on a supermarket in Estonia or Romania or landing on a residential building and potentially killing dozens and dozens of people," Shea warned.

He added that such an escalation would trigger a much more "serious" response than the recent incident.

Shea urged NATO to see the recent violation as a "timely warning" that will force the Alliance to "move expeditiously in a direction of putting greater air defense assets into Eastern Europe".