Defence in Depth? The Centrality of the Baltic Sea for Great Power (Russia-NATO) Rivalry, Competition and Escalation.

The core argument of this paper is that for both Russia, NATO and many of the Baltic littoral states, their growing antagonism and mutual suspicion is likely to draw them into a growing pattern of rivalry at sea in the Baltic Sea. This is in part because escalation on land would quickly reach untenable thresholds. This is somewhat ironic and far from politically straightforward, given that the Baltic states themselves are focused on immediate territorial defence, protection from internal subversion, or exotic threats in cyberspace. As they improve their land defences against Russian 'little green men' do they leave their 'back door'-the Baltic Sea-comparatively open to Russian maritime adventures? For NATO, Sweden and Finland, a core security problem is that the Baltic states on land lack strategic depth for credible conventional defence. To explore these issues this paper draws on NATO historical doctrines as regards similar defence-in-depth dilemmas during the later Cold War, and on operational planning insights as suggested by recent Russian and NATO military exercises. Even if one assumes a Russian threat to the Baltics is implausible in the face of Article 5 guarantees, the fact they can be easily overrun demands serious contingency planning for all 'rivals'. In particular it encourages a much deeper and wider spatial 'battlespace' which embraces the eastern Baltic, pivoting on the strategic Swedish island of Gottland. To defend the Baltic States NATO must plan to do so from the wider Baltic Sea. For Russia, the sea is essential to support their garrison at Kalingrad, but it also represents a comparatively 'safe space' to probe any desired escalation, rather than on land. The sea is a politically subtle space to engage in symbolic and rhetorical shows of force and intimidation at sea, which crucially skirt the threshold of a militarized inter-state disputes. The Baltic Sea is also essential for Russian trade and for energy flows, such as the controversial Nordstream 2 project. Moreover, rival energy flows, notably growing US sourced LNG tanker traffic to the Baltic states is utterly maritime dependent. In conclusion, at multiple levels of analyses, the Baltic sea is likely to witness both increased maritime rivalry and prioritization, as long as the wider relationship between Russian and the west remains so tense.