Russia’s mobilisation of troops at the borders with Ukraine followed by an attack on that country prompted NATO to increase its military presence on the eastern borders of the Alliance. In addition to ad hoc measures, the allies on 24 March at the Brussels Summit approved the decision to increase the size and number of battlegroups deployed on the Eastern Flank from four (in Estonia, Lithuania, Latvia, Poland) to eight (additionally in Bulgaria, Romania, Slovakia, and Hungary). They also announced the acceleration of NATO’s adaptation to the new strategic realities by significantly enhancing defence and deterrence capabilities. As suggested by the NATO secretary general, a complete shift in the approach to deterrence is necessary. Decisions on this matter may be approved at the Madrid Summit in June when NATO will approve the new strategy.

Russian Aggression Against Ukraine—Threats to NATO

The Russian invasion of Ukraine has increased the risk to NATO of a possible Russian attack on Alliance territory. During the war, Russia has threatened NATO states with attacks on warehouses and convoys of military support for Ukraine. The statements by Russian politicians also indicate that the Alliance must be prepared for at least the threat of the use of nuclear weapons in the event of an escalation of the conflict. Through this rhetoric, Russia is trying to divide the West and weaken its response to the Russian aggression, which comprises support for Ukraine and sanctions against Russia. Although Russia has failed to achieve its main goal of forcing a change of power in Ukraine, it is still striving to subjugate the country. The harder it is for Russia to achieve these goals the more it increases the risk the Russians may use weapons of mass destruction in Ukraine, which could also pose a threat to Alliance members.

The strategic threat to NATO is also related to Russia’s broader goals. In December, Russia issued an ultimatum to NATO and the U.S. demanding an end to the Alliance’s enlargement policy (the so-called open door policy), the withdrawal of NATO and U.S. troops from newer member states to pre-1997 positions, and the adoption of legally binding agreements that would limit NATO’s ability to support allies and partners neighbouring Russia. The fulfilment of these conditions, which were included in proposals of treaties between Russia and the U.S. and NATO, would mean the formal recognition of a Russian sphere of influence in Central and Eastern Europe covering a large part of Alliance territory. Because the Alliance flatly rejected these demands, it cannot be ruled out that Russia will intensify its aggressive actions against NATO to try to increase the risk of a conflict and in an extreme case may even seek direct confrontation with the Alliance. Russia’s goal in such a conflict would be to seize part of NATO territory while creating a credible risk of nuclear escalation to intimidate the Alliance to prevent it from countering Russian troops on its territory and thus forcing the West to accept the Russian demands.

For several years, Russia has been stepping up hybrid actions against Western states to create and exploit divisions in the Alliance and weaken the West’s ability to react quickly and decisively to Russian aggression. It has also intensified the anti-Western propaganda directed at Russian society in which the West is presented as an existential threat to Russia. Public opinion polls indicate that a significant proportion of Russians would be ready to support a war with the Alliance. A possible decision about such an attack would be influenced by many factors, including the ability to mobilise forces quicker than NATO to gain regional superiority over the Alliance, the ability to launch an attack from Kaliningrad and Belarus to cut off the Baltic states from NATO support, and an assessment of the Alliance’s determination to restore the status quo in the face of the threat of nuclear escalation.

Limitations of Deterrence and Defence Policy

The increase in threats from Russia in recent years prompted NATO to gradually strengthen its defence and deterrence policy. However, all actions taken since the beginning of the Russian aggression against Ukraine in 2014 are subject to political limitations that weaken their credibility. The political considerations result from the agreement signed in 1997 with Russia—the NATO-Russia Founding Act (NRFA)—in which the Alliance declared that as long as the security environment does not change, it will not deploy significant combat forces (informally understood as greater than an army brigade) on the territory of new member states. This self-imposed restriction was intended to reduce the risk that Russia would treat NATO as a threat and was supposed to create the political conditions for the Alliance’s enlargement. Although the Alliance announced that a collective defence mission would be carried out through necessary reinforcements, exercises, and the development of the necessary infrastructure, differences in the threat perceptions, insufficient defence spending, and the provisions of the NRFA made it difficult to undertake such activities. The Alliance did not hold regular exercises based on collective-defence scenarios and NATO headquarters and multinational forces were not adapted to high-intensity conflict. No major NATO commands were deployed to the territory of the new member states.

This policy, supported by attempts to build a partnership with Russia, did not change the Russian approach to NATO but took on an increasingly hostile character. Although the Alliance did not pose a military threat to Russia, its enlargement hampered Russia’s plans to establish a new sphere of influence in Central and Eastern Europe. By invading Georgia in 2008 and Ukraine in 2014, Russia demonstrated that it was determined to forcibly create such a zone by resorting to military power and undermining the territorial integrity of states in its neighbourhood. At the same time, it announced intensive modernisation of its military potential and intensified its aggressive hybrid actions towards the West, particularly through propaganda, disinformation, interference in elections, and aggressive military signalling, which included demonstrations of the will to use nuclear weapons in a conflict with NATO.

It was only after Russia’s annexation of Crimea in 2014 that NATO decided to strengthen its defence and deterrence capabilities. Member state troops appeared on the Eastern Flank, but they were not put under NATO command to carry out the collective defence mission and were primarily of political significance. The Alliance began to build up the necessary command structures and strengthened the multinational forces (NRF) that could be deployed to the Eastern Flank in response to a threat. In 2017, in the face of intensifying aggression by Russia, NATO deployed multinational battlegroups (about 1,000 troops each) to the Baltic states and Poland, although these did not exceed the brigade level and had a rotational character. The presence of multinational units served as a signal that Russia would not be able to divide the Alliance and weaken its response to possible aggression but its ability to defend the Eastern Flank was still based on much larger forces that would have to be deployed during a crisis. The Alliance and some individual members emphasised that the introduced measures were conducted in the spirit of the NRFA. This weakened the Russian propaganda against NATO but also indicated political problems within the Alliance related to the deployment of troops in the countries of the Eastern Flank.

The full-scale Russian invasion of Ukraine on 24 February forced the Alliance to further strengthen its defence and deterrence capabilities. NATO increased the presence of troops on the Eastern Flank and increased the readiness of forces that can be deployed as reinforcements. However, the size of the troop units still does not exceed the level of a brigade, and the forces are rotating. During the special NATO summit on 24 March, the Allies were unable to agree a joint communiqué on the NRFA. The measures taken ensured a sufficient level of security for the allies so that some of them could provide substantial support to Ukraine, significantly strengthening its defence capacity. NATO members and partners also imposed severe sanctions on Russia. At the same time, some allies were reluctant to support Ukraine with “heavy weapons”. While the effectiveness of the Russian threats against NATO, including the nuclear kind, is difficult to assess, they probably influenced the calculations of the scale and type of support provided to Ukraine.

Conclusions and Recommendations

The war in Ukraine has led to an unprecedented increase in the threat to NATO members that will persist over the long term. The chances that the war will end with an agreement acceptable to both Russia and Ukraine are slim. Although Russia has not achieved its main goal of subjugating Ukraine completely, these attempts will be continued in the future. On the other hand, NATO members will continue their support for Ukraine, which will cause constant tensions between Russia and the Alliance, leading to further Russian revanchism and increasing the risk of limited Russian attacks on NATO territory and the threat of an escalation to a full-scale confrontation. Russia also will not abandon its goals of a sphere of influence covering part of Alliance territory. While limited attacks on NATO territory are more likely than full-scale aggression, the risk of such a scenario has increased significantly. Russia’s actions in Ukraine, which have included widespread intentional attacks against civilians and civilian infrastructure, suggest that similar tactics could be used on the territory of NATO's eastern members. This makes the Alliance's defence and deterrence strategy, which is based on the ability to send reinforcements and liberate lost territories, too risky and costly, and as such, not credible.

Until the full-scale invasion of Ukraine by Russia, the West had not imposed significant costs on Russia in response to its aggressive policy. NATO also did not have the necessary capacity to provide credible defence and deterrence and was not prepared to renounce its self-limitations regarding defence and deterrence policy. This is likely to have influenced Russia’s cost-benefit calculations regarding the attack. Russia has demonstrated its readiness to bear the high risks and costs associated with the pursuit of its strategic goals. Although Russia’s losses in Ukraine will in the short term weaken the credibility of a threat of war with NATO, Russia’s potential is likely to be rebuilt. NATO’s continued lack of capabilities to conduct the collective defence mission may encourage Russia to further increase the risk of conflict, which may weaken the determination of individual states to strengthen defence and deterrence policy, support Ukraine, and impose further sanctions on Russia.

Since Russia has once again concentrated significant forces under the guise of exercises and used them in its aggression against a neighbouring country (as also seen in 2008 before the attack on Georgia and in 2014 before the annexation of Crimea), the Alliance must now assume that any large-scale exercises by Russia close to NATO borders serve as preparation for aggression. As a result, Russia’s military pressure may have a greater impact on threat perceptions and the political cohesion of NATO and the stability of individual members than before.

Russia’s decision to invade Ukraine and the course of the conflict also indicate that the Russian political leadership had a wrong assessment of the chances of achieving its goals and the costs associated with the aggression. Similar mistakes can be made with the assessment of NATO’s determination to defend its members. That is why Alliance policy cannot be based on ambiguous signals that may be misinterpreted by Russian decision-makers. NATO’s unilateral compliance with the 1997 political commitments increase the risk that Russia will treat a conflict with NATO as a rational way to achieve its strategic goals. Despite attempts to strengthen the credibility of defence and deterrence, Russia may decide that the status of NATO’s Eastern Flank remains open for negotiations. The lack of consensus on rejection of the NRFA also creates the risk that during potential future Russian aggression, some allies will block the decision to send necessary reinforcements to the Eastern Flank, hoping that this will prevent a dangerous escalation.

To minimise the risk of further Russian aggression, a fundamental change in the approach to defence and deterrence in the long term will be necessary. To do this, NATO should take the following steps:

• The Alliance’s new strategy to be endorsed during the NATO Madrid Summit in June should refer to Russia as a major military threat to NATO in the long term, underlying a fundamental change in the Euro-Atlantic security system caused by Russia’s aggressive policy. The strategy should emphasise the priority of the collective defence mission, the credibility of which is essential for the Allies to be able to effectively carry out other missions (crisis response and cooperative security). A change in deterrence and defence policy will be the essential condition for NATO to maintain political cohesion and adapt to other threats and challenges such as terrorism, instability in the southern neighbourhood, and the increasingly aggressive China.
• The collective-defence mission must be backed by a credible defence and deterrence policy that requires the development of an appropriate NATO force and command structure, constantly updated defence plans, exercises, and the development of military and technological capabilities. The basis of the defence and deterrence policy in the military dimension should be the concept of “forward defence”, which assumes the presence of Alliance commands and forces on the Eastern Flank capable of effectively defending the territory in the event of a Russian attack. The purpose of such forces should be to prevent Russia from taking control of any part of NATO territory in a rapid conflict and to maintain the ability to deploy reinforcements. In the states most exposed to a Russian attack—Estonia, Lithuania, Latvia, and Poland, which serves as a regional defence hub—multinational battlegroups of at least a brigade size should be stationed. As the presence of U.S. forces has a unique deterrent value, NATO battlegroups should include a significant component of American troops. NATO also should be able to deploy a force of at least division size to each of the Baltic states and Poland within days of a political decision. As part of changes in the command structure in Poland, an additional allied land forces command should be created (similar to the one based in Izmir, Turkey). Such force posture should be augmented with prepositioned stocks of equipment, expansion of the Central Europe Pipeline System (CEPS) to supply fuel to NATO forces on the Eastern Flank, and more frequent and larger exercises. The change in strategy should be supported by strategic communication (statements by the secretary general, NATO communiques) that the presence of NATO forces or bases may become permanent and that the Alliance does not feel bound by the limitations of the NRFA.
• The risk of Russia using weapons of mass destruction in Ukraine and the nuclear threats against the Alliance require NATO to maintain freedom in shaping its nuclear deterrence policy. For the time being, effective deterrence does not require a change in the current nuclear policy, which is based in part on the 1996 declaration (repeated in the NRFA) that the Alliance had no intention of deploying nuclear weapons to the new member states. Strengthening the credibility of deterrence can be achieved through planning and exercises, the implementation of new weapons systems (including F-35 aircraft) and greater involvement of allies in conventional operations as part of nuclear missions. NATO should, however, place more emphasis on the ability to counter Russia’s nuclear threats. This requires faster and coordinated messaging, also at the level of individual states, by pointing out that NATO is a nuclear alliance with a credible deterrent potential.