A reduction in the US commitment to NATO’s European defense could alter Russia’s military calculations in the Baltic region and increase the risk that a conflict with Europe escalates to nuclear confrontation, Harvard Kennedy School nuclear security researcher Spencer Warren said. Russia could view Lithuania, Latvia and Estonia as potential targets, he said, while the likelihood of nuclear use would be harder to assess if Russian forces faltered in a conventional war.
Warren studies Russia’s nuclear arsenal and its doctrine for using nuclear weapons. Russian President Vladimir Putin has the final authority over their use, he said, and Moscow’s aim of rebuilding a sphere of influence in the former Soviet Union is intertwined with the risk of escalation through nuclear deterrence. For markets, the assessment underscores uncertainty around Europe’s security framework and the implications for defense spending and nuclear deterrence. The military scenarios remain analysis, not a prediction that war will occur.
Danish assessment flags risks along NATO’s borders
Denmark’s Defence Intelligence Service recently assessed that the risk of Russia launching a limited military attack against one or more neighboring NATO countries is rising, with such an action potentially possible in the coming months. Its scenarios outline three timelines: Russia could be capable of waging a localized war against a neighbor in about six months; be ready for a regional war involving several Baltic states within two years; and have the capacity for a large-scale war on the European continent in about five years.
Warren said that if Russia concluded it should attack the Baltic states soon, other actions in the coming months would warrant close attention as possible precursors to a regional conflict. Lithuania, Latvia and Estonia regained independence after the collapse of the Soviet Union and later joined NATO. Their armed forces are relatively small, and their defense relies heavily on the alliance’s collective-defense commitment.
Danish intelligence officials have also warned that Russia could misjudge whether NATO would respond collectively to an attack on a member, particularly if Moscow believed the United States was unable or unwilling to support its European allies. Article 5 of the NATO treaty treats an attack on one member as an attack on all, but any response would still depend on the political and military decisions of member states.
Conventional defenses and the risk of nuclear escalation
Warren said NATO’s 31 members other than the United States could still mount a collective defense against Russia if fighting remained conventional. That would not guarantee victory or prevent severe losses. He pointed to the advanced aircraft and tanks operated by Nordic countries, as well as their NATO-trained forces. A central question, he said, is whether Russia could seize the Baltic states quickly and withstand a counteroffensive by European forces.
If Russia failed to take control of the Baltic region rapidly, the conventional balance could turn against Moscow. But it is difficult to predict whether a war would remain conventional. Warren said Russia could feel pressure to use nuclear weapons to avert defeat if it faced a military setback or if NATO’s European forces appeared likely to advance into Russian territory, including Kaliningrad. He also identified the direction of St. Petersburg as a potential point of concern for Russia.
A direct Russia-Europe conflict would carry a serious risk of nuclear escalation, Warren said. Moscow might nevertheless hold back if it believed nuclear use would bring the United States into the conflict or prompt action by France. He considers the latter scenario less likely, but not impossible. Russia’s nuclear-use doctrine is generally viewed as broader than those of the United States, the United Kingdom and France, while decisions in any specific conflict would remain uncertain.
Putin’s nuclear warnings and France’s response
Putin has recently spoken again about the risk of nuclear conflict, saying a nuclear confrontation could push the world toward an abyss and that there could be no guarantee the weapons would never be used. He also said Russia has strike capabilities other countries do not possess. Russia has one of the world’s largest strategic and tactical nuclear arsenals, and its nuclear forces remain a key part of its status as a major power.
Five days after Putin’s latest round of nuclear threats, French President Emmanuel Macron watched the nuclear-powered submarine Le Vigilant launch a nuclear-capable missile off the coast of Brittany. Macron described the test as an important demonstration of the credibility of France’s deterrent. France is also modernizing its nuclear forces and discussing a broader nuclear-protection role for European allies.
Researchers at the Federation of American Scientists estimate that France has about 290 nuclear warheads, with roughly 80 retired warheads awaiting dismantlement, for a total stockpile of about 370. In April 2025, while French nuclear-capable aircraft were deployed to northern Sweden, France’s ambassador to Sweden said the French nuclear umbrella also applied to allies, including Sweden.
France’s deterrence arrangements could affect how Europe seeks to strengthen its security if the US commitment changes, but their role would depend on national policies, military deployments and decisions made during a crisis. Warren said Europe would likely have the advantage if fighting stayed conventional and Russia was tied down in the Baltic region. If nuclear weapons were used, however, the course of events would quickly move beyond what conventional military scenarios can reliably establish.