Explained: NATO's presence in Eastern Europe

Since 2014, when Russia annexed Crimea, NATO has been gradually increasing its military presence in Eastern Europe.

There are now more than 4,000 NATO troops in the Baltic states and Poland, with the alliance also sending extra troops to Ukraine as Russian forces continue to build up on the country's border.

But what is NATO's presence across the wider region?

• NATO missions: Where is the alliance operating?
• NATO bolstering eastern Europe – what is the alliance deploying amid Russia tensions?
• How did tensions lead to potential Russia invasion of Ukraine?