Defending Ukraine

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Russia’s invasion of Ukraine is the biggest test of the liberal world order since the Second World War. It also represents an implicit threat to Ukraine’s neighbors, many of whom are members of the NATO alliance. NATO members have so far limited themselves to sending aid to Ukraine. However, as the conflict continues, calls to directly intervene in the conflict have grown. The United States must determine whether to support Ukraine directly.

Students will understand that military intervention, especially against a powerful and nuclear-armed country such as Russia, carries huge risk.

The Situation

Russian President Vladimir Putin’s invasion of Ukraine has killed thousands,  and driven more than two million Ukrainians to flee to surrounding countries.  Ukrainian forces have mounted a stiffer defense than analysts predicted, but observers fear this will not last. Paradoxically, the longer Ukrainian forces frustrate Putin’s offensive, the greater the chance that he will resort to indiscriminate attacks on civilian centers. Moreover, the possibility remains that the Kremlin will resort to using weapons of mass destruction to achieve victory. As the war continues, it could spill over or lead Putin to expand his ambitions into neighboring countries. Many of the countries adjacent to this conflict are members of the North Atlantic Treaty Organization (NATO)— an alliance of thirty North American and European democracies who have committed to mutual defense in the event of an attack. This would precipitate a broader war between NATO and Russia that could cause mass devastation in Europe and have worldwide ripple effects. At the extreme, such a war risks a catastrophic nuclear exchange.

The United States and NATO have an urgent interest in assisting Ukraine and keeping the fighting confined within its borders. So far, the U.S. and NATO response has focused on indirect measures, imposing crippling economic sanctions and supplying Ukraine with billions of dollars’ worth of weapons . This strategy could increase the price of Putin’s invasion to the point where he would consider negotiating a ceasefire. The hope is that sanctions and aid will not provoke Russian retaliation. As the war grows deadlier, however, calls for more direct intervention have grown. Many policymakers doubt arms transfers are sufficient to turn the tide in Ukraine. Others—especially in the Baltic countries on NATO’S eastern flank— also fear that escalation is inevitable. Former Soviet republics believe that the conflict will spread if not from an inadvertent spillover from Ukraine, then from Putin’s imperial ambitions.. Moreover, Russian forces have suffered early setbacks in their invasion, sparking speculation that they are not as strong as initial analyses suggested. If these assessments are true, intervening before a NATO ally is attacked could give the United States a decisive advantage. An intervention would allow the United States to stop Russia in its tracks and guarantee the safety of nearby NATO members.

Two principal options for a direct intervention exist. The first is to commit to the full-scale defense of Ukraine by deploying ground troops to the country. If assumptions about Russian forces’ weaknesses prove true, this option offers the strongest defense to Ukraine and could safeguard neighboring NATO members’ security. Yet this would trigger the very war that NATO hoped to deter. At best, this option still puts thousands of U.S. service members at risk. If it goes wrong, it could lead to a devastating land war in Europe. At worst, direct U.S. involvement could drive Putin to resort to a nuclear attack. The second option is to support Ukraine by establishing a no-fly zone over Ukraine's airspace. This would prevent Russian airstrikes and rob Russia of one of its chief military advantages. However, Russia is unlikely to simply abide by a no-fly zone. NATO air forces would need to enforce it by directly targeting Russian planes and air defense systems. Therefore, even this limited option would likely amount to a NATO war with Russia . Critics of the idea add that, on top of its risks, a no-fly zone fails to curb Russian forces from bombarding Ukrainian targets with ground artillery. So far, NATO countries have taken any form of direct military response off the table. But as the war in Ukraine drags on, policymakers need to carefully consider how they can help defend Ukraine, while minimizing the risks of triggering a far more devastating war.

Decision Point

As Putin’s offensive in Ukraine continues, onlookers in the United States and Europe are growing increasingly concerned. As the war drags on, Russian forces could step up indiscriminate bombardments or resort to using weapons of mass destruction to achieve victory. Compounding these concerns are fears that the conflict could expand into a neighboring NATO country, possibly triggering a broader war among nuclear-armed powers. With the war in Ukraine showing no sign of letting up, the president has convened the National Security Council (NSC) to discuss how the United States and its NATO allies should respond. NSC members will need to carefully consider how to aid Ukraine’s defense while safeguarding against a potentially catastrophic escalation.  

NSC members should consider the following policy options:

  • Provide full direct defense to Ukraine, including by committing U.S. ground troops to Ukraine and calling on NATO allies to do the same. This option offers the possibility of halting devastation in Ukraine and ending the war before it can spread into other countries. Yet it carries an immense risk of escalating the conflict into a broader, more devastating war.
  • Provide limited direct defense to Ukraine, including by declaring a no-fly zone over some or all of Ukraine’s airspace. This option could prevent the worst of Russia’s aggression and help to safeguard civilian centers and humanitarian corridors. This policy option does not include the greater risk to personnel that a full commitment of U.S. and allied forces would entail. However, if Russian forces breached the no-fly zone, this option would risk drawing NATO into direct combat operations against Russia, triggering war.
  • Continue providing indirect defense, including by supplying Ukraine with arms, intelligence, and financial assistance. This option minimizes—but does not eliminate—the risk of triggering escalation. However, it cannot guarantee that the war will not still expand into a NATO country. This policy option provides the least assistance to Ukraine, likely only slowing an increasingly devastating Russian offensive.

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