|Russian military flights into Europe have increased over the past year|
NATO has responded to Russia's incursions into Ukraine by stepping up its ties with Kiev and bolstering air patrols and exercises with its eastern and central European members.
Russia in turn has decided to pursue a more active, many might say a more aggressive, military policy of its own, returning to the sorts of flights and activities from the Cold War years that were used to regularly test out NATO defenses.
The European Leadership Network, a London-based think tank, has produced a detailed study of this more assertive Russian activity.
Entitled Dangerous Brinkmanship: Close Military Encounters Between Russia and the West in 2014, it chronicles almost 40 specific incidents that have occurred during the past eight months.
It says these "add up to a highly disturbing picture of violations of national airspace, emergency scrambles, narrowly avoided mid-air collisions, close encounters at sea and other dangerous actions happening on a regular basis over a very wide geographical area".
|Key incidents by date|