Since the early 2000s, Ukraine has looked westward, expressing a clear and consistent ambition to join the North Atlantic Treaty Organization (NATO). For Ukraine, membership isn’t just about political alignment; it’s about survival. The core of the NATO alliance is its principle of collective defense, enshrined in Article 5, which states that an attack on one member is an attack on all. This security guarantee is precisely what Ukraine needs.
Despite widespread support from many NATO allies and a deep partnership that has grown over the years, Ukraine’s membership remains off the table, at least for now. The ongoing war with Russia has created a complex and perilous situation. While NATO’s door is officially open, admitting Ukraine during an active conflict would have immediate and severe consequences, not just for the alliance but for the entire world.
This post will explore the specific reasons why Ukraine cannot join NATO at this moment. We’ll examine the formal requirements for membership, the practical and political barriers presented by the war, and what the future might hold for Ukraine’s long-term security aspirations.
What Does It Take to Join NATO?
Joining NATO is a rigorous process. Aspiring countries must meet a set of political, economic, and military criteria outlined in the Membership Action Plan (MAP). The goal is to ensure that new members can contribute to the alliance’s security and uphold its democratic values. Key requirements include:
- A stable democratic system: This includes a functioning market economy, a commitment to resolving conflicts peacefully, and a firm respect for the rule of law and human rights.
- Civilian control of the military: The armed forces must be under the democratic and civilian control of the government.
- Respect for borders and international law: Candidates must have no unresolved territorial disputes with their neighbors. This is a critical point in Ukraine’s case.
- Ability to contribute to NATO’s defense: Members must have the military capability to contribute to collective defense and NATO missions.
- Compatibility with NATO forces: The country’s military must be able to operate alongside other NATO members’ forces, which involves standardizing equipment, training, and procedures.
Ukraine has made significant strides in these areas, especially since 2014, modernizing its military and strengthening its democratic institutions. However, several major obstacles remain.

The Five Barriers to Ukraine’s NATO Membership
Even with its progress, Ukraine faces insurmountable hurdles to joining the alliance while the war with Russia continues.
1. The Ongoing War and Article 5
The most immediate and significant barrier is the active conflict. Admitting a country that is already at war would automatically trigger Article 5. The moment Ukraine became a member, all 32 NATO allies—including the United States, United Kingdom, France, and Germany—would be legally obligated to treat Russia’s invasion of Ukraine as an attack on their own soil. This would immediately draw the entire alliance into a direct, full-scale war with a nuclear-armed Russia. NATO’s primary goal has been to support Ukraine without becoming a direct combatant, and admitting Ukraine now would cross that line.
2. Unresolved Territorial Disputes
NATO has a long-standing policy of not admitting countries with ongoing territorial disputes, particularly those involving a military conflict. Russia’s illegal annexation of Crimea in 2014 and its occupation of territories in the Donbas, Kherson, and Zaporizhzhia regions create a significant obstacle. Admitting Ukraine would mean inheriting these disputes, which goes against the alliance’s aim to enhance, not import, security challenges. Until these territorial issues are resolved, membership is highly unlikely.
3. The Unthinkable Risk of Escalation
Beyond the legal trigger of Article 5, admitting Ukraine now would carry an immense risk of escalating the current conflict into a global confrontation. Russian President Vladimir Putin has repeatedly framed NATO expansion as an existential threat to Russia. While this is a pretext for his aggression, bringing Ukraine into the alliance during the war could be perceived by Moscow as a direct declaration of war by the West. The potential for this to spiral into a Third World War, possibly involving nuclear weapons, is a risk that NATO leaders are unwilling to take.
4. The Need for Internal NATO Consensus
NATO operates on the principle of consensus, meaning all 32 members must unanimously agree to invite a new country. While many members, particularly those in Eastern Europe like Poland and the Baltic states, are strong advocates for Ukraine’s membership, others are more cautious. Countries like Hungary and, to some extent, Germany and Turkey have expressed concerns about provoking Russia further or the readiness of Ukraine to join. Without unanimous agreement, the invitation cannot be extended.
5. Ongoing Reforms in Ukraine
While Ukraine has made remarkable progress in fighting corruption and strengthening its governance, the journey is not complete. Before the full-scale invasion, international observers noted that Ukraine still needed to make further reforms in its judicial system and ensure long-term political stability. NATO requires its members to be resilient, stable democracies, and while the war has shown Ukraine’s incredible national unity, the institutional reforms required for membership will likely need to be finalized once the conflict has ended.

NATO’s Current Stance and Ukraine’s Alternatives
For now, NATO’s position is one of unwavering support short of direct intervention. The alliance and its members have provided Ukraine with billions of dollars in weapons, training, and financial aid. At the 2023 Vilnius Summit, NATO allies reaffirmed their 2008 Bucharest declaration that “Ukraine will become a member of NATO” but stopped short of providing a concrete timeline or formal invitation.
In the meantime, Ukraine is pursuing other avenues to secure its future:
- Bilateral Security Guarantees: Ukraine has signed long-term security agreements with several individual countries, including the United Kingdom, France, and Germany. These agreements commit the signatories to provide sustained military and financial support but do not include a collective defense clause like Article 5.
- EU Integration: Ukraine has been granted candidate status for the European Union, and accession talks are underway. While the EU is primarily a political and economic union, it does have a mutual defense clause, though it is less robust than NATO’s.
- Military Modernization: Ukraine continues to align its armed forces with NATO standards, adopting its tactics, equipment, and command structures. This not only strengthens its ability to defend itself but also ensures it will be ready for seamless integration into the alliance when the time comes.
The Path Forward
Ukraine cannot join NATO while the war with Russia rages on. The risks of triggering Article 5, escalating the conflict, and the lack of internal consensus make it impossible in the current circumstances. The door to membership, however, remains open.
Ukraine’s long-term path to joining the alliance depends heavily on the outcome of the war and its ability to resolve its territorial disputes. The country’s bravery and its commitment to democratic values have earned it the admiration of the world and a place at the heart of the Western security debate. While a NATO badge may not be on Ukraine’s uniform today, the groundwork is being laid for it to be there in the future.
Frequently Asked Questions
Why can’t Ukraine join NATO during the war?
Ukraine cannot join NATO during the war primarily because it would trigger Article 5, the alliance’s collective defense clause. This would legally require all 32 NATO members to enter into a direct war with Russia, leading to a massive and dangerous escalation.
Has NATO ever promised Ukraine membership?
Yes. At the 2008 Bucharest Summit, NATO leaders declared that Ukraine “will become a member of NATO.” This promise has been reaffirmed multiple times, but the alliance has never provided a specific timeline or a formal Membership Action Plan (MAP).
Could Ukraine join NATO after the war ends?
It is possible, but it will depend on the terms on which the war ends. Ukraine would likely need to have resolved its territorial disputes with Russia and have a clearly defined, internationally recognized border. It would also need to complete its democratic and anti-corruption reforms and gain the unanimous approval of all NATO members.
What is Article 5, and why is it so important?
Article 5 is the cornerstone of the NATO alliance. It states that an armed attack against one member shall be considered an attack against them all. This principle of collective defense ensures that smaller members are protected by the military might of the entire alliance, including the United States.
Do all NATO members support Ukraine joining?
Support is strong but not unanimous for immediate membership. Eastern European countries like Poland and the Baltic states are very vocal supporters. However, other members, such as Hungary, have been openly skeptical, while countries like Germany have been more cautious, fearing a direct confrontation with Russia.
How does Russia view Ukraine’s potential NATO membership?
Russia vehemently opposes Ukraine joining NATO. President Putin has long claimed that NATO’s eastward expansion poses a direct threat to Russia’s security interests, and he used this as one of the main justifications for launching the full-scale invasion in 2022.
