Russian President Vladimir Putin has given NATO a set of demands.
He wants NATO to halt its expansion and withdraw troops or military equipment from countries neighbouring Russia like Ukraine, but also alliance nation members like Estonia, Latvia and Lithuania.
The US and NATO have rejected key Russian security demands for easing tensions over Ukraine, but have left open the possibility of future talks with Moscow to discuss other issues like arms control, missile deployments and ways to prevent military incidents.
Emily Ferris, Research Fellow, Royal United Services Institute, said NATO's movement of "security architecture" to Eastern Europe's former Warsaw Pact states, including Estonia and Poland, is seen by Russia as "somewhat of an aggressive act".
According to Russia, NATO must leave Latvia, Lithuania, Poland, Estonia, Czech Republic, Slovakia, Hungary, Romania, Bulgaria and Albania – all formerly part of the Moscow-led Cold War alliance but now fully-fledged members of NATO.
Russia considers countries like Ukraine "within its sphere of political and security interests," Ms Ferris added.
Estonia hosts the UK-led NATO mission Operation Cabrit, while the US takes the lead on similar projects in Poland.
Watch: NATO and Russia agree more high-level talks despite building tensions.
Meanwhile, NATO expansion to include Georgia and Ukraine is also off the table, according to Moscow. This has been rejected by NATO.
Regarding the potential for a compromise, Ms Ferris believes there is no "political will" for further escalation on Russian borders and that a new generation of Russians have less appetite for conflict with neighbouring states.
The "most likely" outcome would be another version of the Minsk Protocol agreed in 2014, which sought to end fighting in the Donbas region of Ukraine following Russia's annexation of Crimea, she added.