NATO: Toward the Ankara Summit

• Collective defense is the foundation of NATO. NATO has invoked the Article 5 collective defense guarantee only once, after the terror attacks of September 11, 2001.
• Positive trends in the war in Ukraine may have shifted US attitudes; some NATO members may also be willing to contribute to stabilizing the Strait of Hormuz once conditions permit.
• The US announced significant drawdowns both in current forces in Europe and in those planned for deployment in a crisis under NATO’s Force Model. European countries are racing, but in some areas struggling, to backfill those requirements.
• Separately, discussions continue on a greater European defense identity, in connection with the EU and with non-EU members such as the UK, Ukraine, Türkiye, and Norway.
• However, one should not expect major advances at the Ankara Summit; success will simply involve smoothing over transatlantic tensions and reinforcing the principle of collective defense.

An Enduring Alliance

NATO was formed in 1949 with 12 original members (the US, Canada, and a number of countries in Western Europe);¹ Greece and Türkiye joined in 1952, and West Germany in 1955. The organization was first formed for mutual defense against the USSR. The Alliance has since grown to 32 with the addition of most of the former members of the Warsaw Pact, the Baltic States, and most countries of the former Yugoslavia. While NATO’s theater of operations is limited by treaty to the Euro-Atlantic area, it also has partners in Ukraine, the Caucasus, Central Asia, and some nonaligned members of the Organization for Security Cooperation in Europe. Japan, South Korea, Australia, New Zealand, and several other countries are global partners.

NATO’s founding treaty² contains the fundamental principle of NATO: the collective defense guarantee in Article 5, the principle that an attack on one Member is an attack on all Members. Article 5 has been invoked only once, in 2001 after the September 11 terror attacks in the US. NATO was also designed to promote stability in Europe as the continent recovered from the economic devastation of World War II, allowing them to focus on economic recovery and democratic strength and to serve as a guarantee of US commitment to European security.

Throughout the years, there have occasionally been strong divisions in the Alliance: France left the unified military command in 1966 (and fully rejoined only in 2009);³ Greece and Türkiye left NATO briefly following their war over Cyprus; deployment of a new generation of nuclear missiles in the 1980s provoked controversy in Europe; and more recently, the US has pressed over several Administrations for greater defense spending by European nations. But the reasons to keep the Alliance together -- in particular, deterrence against the Soviet Union and now against other external threats -- have remained strong and overwhelm any sense that NATO is obsolete. NATO has also expanded into other efforts such as crisis management, peacekeeping, defense against cyberattacks and newer threats, and training and building relations with partner countries.

Through it all, the Alliance has endured. Even decades after the end of the Cold War, NATO is the foundation of European security and still protects US interests in the region and beyond. Few alliances in history have lasted for nearly 80 years, and the Alliance has led to the longest peace without a general war in Europe in centuries.

Backdrops to the Summit

Four issues in particular form important backdrops to the Summit -- defense spending and the US’ planned withdrawal of forces from NATO planning and from Europe, the conflict in Ukraine, the war in Iran, and continued tensions over Greenland and Arctic security.

Defense spending

In 2014, after the Russian annexation of Crimea, NATO members committed to reach a goal of 2% of GDP for defense spending. (The current highest spending member is Poland, at 4.3% of GDP).⁴ By 2025, all Allies had met or exceeded the target. In 2025, the target was increased to 5% of GDP by 2035, divided among 3.5% of GDP for core defense spending (under a common definition) and 1.5% for spending to support defense spending (for instance, cybersecurity, critical infrastructure protection, civil defense, the defense industrial base, and transportation infrastructure important to meet defense plans).⁵ Overall, European defense spending rose 20% in 2025. Most Allies have set targets for spending to be achieved by 2029 or 2030 as interim steps to the 2035 goal. NATO leaders understand the need to move quickly on defense spending and actual purchases of “combat-ready capabilities” as a “shared priority for the Ankara Summit, and for the years ahead” as part of NATO 3.0, “an Alliance rebooted for the modern age.”⁶

The Gulf war

The Gulf war with Iran has also been a flashpoint between the Administration and European NATO Allies. While the UK and Germany did provide basing and overflight rights to US forces during the conflict (while opposing it politically), other countries such as Spain and Italy did not, leading to sharp criticism from the US and warnings of consequences.⁷ Some Allies also note that they were not included in the initial decision to go to war nor in discussions about its progress, and out of area operations must be approved by the entire NATO membership.⁸

Formal NATO operations -- and the Article 5 guarantee of collective defense -- are limited to the Euro-Atlantic area defined in Article 6 of the Washington Treaty, which excludes areas east and south of Türkiye. During the war, NATO defenses were activated when Iranian drones were directed towards Türkiye. But Türkiye did not request invocation of the Article 5 collective defense guarantee, nor did either it or the US request authorization of an out-of-area NATO activity to which Members could contribute if they wished.

Article 4 of the Treaty further provides that NATO Members “will consult together whenever, in the opinion of any of them, the territorial integrity, political independence or security of any of the Parties is threatened.” After the September 11 attacks, the US requested consultations under Article 4 and invocation of the collective defense guarantee under Article 5. This led to approval of an out-of-area action covering NATO involvement in Afghanistan. There had been a similar approval of an out-of-area action covering the war in the former Yugoslavia in the 1990s. However, this year the US did not request Article 4 consultations after it began the war in Iran nor after attacks on US forces in the Middle East. It could have but did not. 

Under the Treaty, therefore, there is no obligation for NATO Members to participate in military action out of the North Atlantic area begun by one State Party to the Treaty when the North Atlantic Council has not invoked the collective defense guarantee. If it were otherwise, the US would have had an obligation to join the UK/France operation in Libya in 2011 and the Central African Republic operation in 2013. It did not then, and European NATO members do not now. 

Still, Iran remains a tension in the transatlantic relationship, one which some European NATO Members are eager to ease. France and Britain had deployed forces to the Mediterranean and Red Sea during the conflict but did not take part in combat (they did in 2024 in repelling attacks in the Red Sea by the Houthis in Yemen on commercial shipping in the Red Sea). Recently, a German newspaper suggested that there may be a NATO mission in securing the Strait of Hormuz⁹ (which would presumably have to be authorized by the Alliance unless it is simply done individually by interested Member States). It is possible that once conditions are in place to support the deal, this type of mission could begin, and it is something to watch at the summit.

Ukraine and the Baltics

Ukraine’s recent successes in both stopping Russian advances and in drone warfare including long-range attacks in Russia itself and in occupied Crimea have changed both the tone and progress of the war,¹⁰ to the point where Ukraine (supported by major European leaders) felt strong enough to propose an immediate ceasefire with Russia and invite negotiations, which Russia rejected. Drone warfare, in fact, is an important strength of Ukraine’s armed forces, one from which the US and European nations are eager to learn. European nations also need to work together on programs such as air defenses, including ballistic missile defense and drone warfare, areas where Ukraine’s experience in the current war offers valuable lessons.¹¹

At the recent G-7 Summit, France noted a “very deep change” and “re-synchronization” of the US position on Ukraine and a “shared commitment to making progress on this issue,” which included a promise to increase sanctions on Russia¹² and a joint sense that Russia is not interested in peace talks. Some European leaders see this as a “moment of reconvergence” on Ukraine between Europe and the US, on which they hope to build. Showing the interrelation of issues facing the Alliance, at the G-7 Summit, the US and some European countries agreed to give licenses to companies in Ukraine to produce missiles and air-defense systems for European countries (and presumably also the US).¹³ 

As the tone of the war has shifted against Russia, there is deep concern in Europe that Russia could attack the Baltics to widen the war.¹⁴ Russia is threatening the Baltics and Poland directly. Indeed, there has been increased drone and other military activity over the Baltics. French fighters intercepted Russian aircraft 11 times and shot down a Russian drone over Latvia; there have been other incidents over Estonia and Lithuania. A Russian drone also crashed nearly 20 miles inside Romania.¹⁵ Russian provocations before NATO Summits in an attempt to divide the Alliance are nothing new but achieve a new prominence given broader concerns over the durability of US commitment to the Alliance.

The Administration continues to oppose admission of Ukraine to NATO and included a goal in the 2025 National Security Strategy of “[e]nding the perception, and preventing the reality of, NATO as a perpetually expanding alliance”; realistically, because every member must ratify the accession of new members, additional members are in any event unlikely even with US support. Similarly, the idea that NATO could expand to be global is incorrect: nations such as Japan, South Korea, and Australia do not meet the geographic criteria of the Washington Treaty.

Arctic security

The sharp tensions in the Alliance in January over US threats to annex Greenland have not been resolved. NATO agreed to convene a working group on Arctic security and expanded activity in the region,¹⁶ but suspicions linger that the US will still seek some form of sovereign rights over at least a portion of Greenland. Depending on how hard the US wishes to press the issue, this could become a flashpoint at the Summit. Denmark has already offered the US access to additional bases.¹⁷

US force drawdowns

More broadly, some Allies have expressed concerns over the extent of the US’ continuing commitment, noting that the foundation of collective defense lies at the heart of NATO.

The US is reducing the number of fighter jets stationed in Europe (by a third),¹⁸ drones, and warships reserved for a crisis,¹⁹ as well as an aircraft carrier and refueling planes,²⁰ even as the US continues to hold the role of Supreme Allied Commander and maintains other assets there. The Administration’s goal is for Europe to take primary responsibility for its conventional defense and to restore “NATO’s core military role and character.” In addition, the US is reportedly canceling a sale of Tomahawk missiles to Germany,²¹ a surprising development given US requests both for European countries to increase defense spending and for European countries to increase purchase of US goods to avoid further imposition of tariffs.

As a result, NATO’s Force Model, which identifies resources deployed in a crisis, is being significantly revised to reflect greater European contributions to backfill losses of US support.²² But the US will continue to deploy nuclear weapons in Europe, and NATO’s Nuclear Planning Group recently reaffirmed that “the strategic nuclear forces of the Alliance remain the supreme guarantee of Allied security and underpin NATO’s extended deterrence architecture.”²³ 

Further, recent US rhetoric has been quite harsh, calling NATO a “paper tiger and a one-way street” and criticizing what it called some European nations’ “focus on gender equity and climate change and defense austerity” instead of “tanks and fighters and air defenses” and saying that its “belief in itself and its civilization” has “cratered.” This leads to concerns among European Allies as to the reliability of the US commitment to collective defense. 

The US will also launch a six-month review of US forces in Europe, designed “to ensure that NATO is moving fast and irreversibly toward Europe leading, stepping up to take primary responsibility for the defense of Europe. It is a review that some countries will fail and other countries will pass with flying colors.” The new review came as a surprise as NATO members focus on ways to backfill previously-announced reductions in US support. The US also sharply criticized some Allies’ declining to participate in or support the war in Iran, calling it “shameful” and stating that full access and overflight rights in any conflict would also be part of the review.

Could the US withdraw?

At a minimum, the recent developments have moved US policy from harsh rhetoric to tangible actions. Formal US withdrawal from NATO, suspending or terminating funding for NATO, or using Federal funds to prepare for NATO withdrawal is prohibited by statute (Section 1250A of the National Defense Authorization Act of 2023) without Congressional approval,²⁴ including a two-thirds vote in the Senate, the same as for ratification of a treaty. This makes formal withdrawal difficult (which in any case would require a one-year period between denunciation of the Treaty and actual withdrawal from the Alliance), but severe pressures on Allies, even including threats of military action as in the controversy over Greenland in January, raise questions as to the value of the US commitment. Still, NATO membership and support for the Alliance has strong bipartisan support in Congress, which will keep funding NATO operations.

European Defense

More broadly, there is something of a change in attitude in Europe, a realization that in the current environment geopolitics and geoeconomics seem linked (for instance in the threat of tariffs on Europe over the war in Iran) and that increased defense spending alone and other concessions will not necessarily simply lead to stronger relations. In any event, the pull of forces away from a growing threat in Europe itself would be challenging. This is precisely the argument in favor of higher defense spending, but Europe cannot both participate significantly in out-of-area operations and increase defenses in Europe at the same time. To do so would leave vulnerabilities to Russia. 

While European leaders remain absolutely committed to NATO, all this also raises the question of common European defense structures. Article 42.7 of the Treaty on European Union²⁵ is a mutual defense clause in the event of “armed aggression” on an EU member’s territory. (It also notes that for EU members that are also NATO members, NATO “remains the foundation of their collective defense and the forum for its implementation.” To that extent, Article 42.7 is part of the “European pillar” of NATO and in some sense even the heir to the “European defense community” proposed at the time the “European Economic Community” was set up in the 1950s, even as leaders hope strengthening the European pillar strengthens NATO itself.

A number of European leaders are seeking to give greater meaning to this clause and other efforts at European collective defense. This development has been strongly accelerated by the war in Ukraine, including funds for joint EU purchases of military items. During the war in Iran, several EU Member States contributed to the defense of Cyprus following an Iranian attack on the British sovereign territory there.²⁶

This unique set of facts -- EU Member States helping the defense of an EU Member State not a member of NATO which is also being defended by a country (the UK) which is a member of NATO but not of the EU -- highlights another reality in European defense: several of the strongest military powers in Europe are not members of the EU. These include the UK, Türkiye, Norway, and of course Ukraine. Any future European defense arrangement therefore is likely not simply to consist of EU members but other nations as well, perhaps moving in some way towards a true European defense community formally separate from, but working in partnership with, both NATO and the EU. Any peace settlement in Ukraine could also involve nations such as the UK and France contributing peacekeepers in their national (not NATO) capacity; Ukraine is also seeking accelerated entry into the EU as part of an overall peace settlement.

Ankara -- And beyond

For the moment, however, most European leaders will be content with a NATO Summit with a minimum of controversy and a focus on positive developments: a change in the war in Ukraine; a ceasefire, however tenuous, with Iran; and higher European defense spending and greater European efforts at defense cohesion. Because NATO is an intergovernmental organization with a Secretary-General, the Summit host also plays a role. This, too, may be grounds for optimism. The US has strong relations with Türkiye, most recently agreeing to sell fighter jet engines for the new Turkish combat aircraft,²⁷ and would not want the Summit to fail lest it reflect poorly on the host.

Still, it would likely be a mistake to expect significant advances in Ankara. Perhaps the strongest result would be to recall that Article 5 was invoked 25 years ago for the defense of the US and to provide some reassurance so that Europe may have confidence that the US would come to the collective defense. Eighty years of success has not meant stasis. Instead, NATO has evolved over the decades and will continue to do so -- with good will and determination on both sides of the Atlantic and a realistic understanding of the military and hybrid warfare threats NATO’s member states continue to face.

Endnotes