NATO (North Atlantic Treaty Organisation): Members, Expansion and India’s Ties

NATO is a military alliance built on a short treaty. This card gives the date, the founders and the words you need.

What happened in 1949?

On 4 April 1949, 12 countries signed the North Atlantic Treaty in Washington, D.C. NATO was born.

The treaty is short. It has only 14 articles and just over 1,000 words. Its core is a joint pledge: each country will help the others if they come under attack.

NATO says the early Cold War made this urgent. The Soviet Union dominated its neighbours in Central and Eastern Europe. It threatened to extend its control further west.

The treaty came into force on 24 August 1949. That was after all signatory states had deposited their ratifications.

Who were the 12 founders?

• Founders: Belgium, Canada, Denmark, France, Iceland, Italy, Luxembourg, the Netherlands, Norway, Portugal, the United Kingdom and the United States.

Which words should I know?

• Ally: NATO’s word for a member country.
• Collective defence: members defend one another if one is attacked.
• Washington Treaty: another name for the North Atlantic Treaty.
• Ratify: to approve a signed treaty under a country’s own rules.
• Accede: to join a treaty that already exists.

Article 5 is the best-known clause. This card gives the treaty’s words and what NATO says they mean.

What does Article 5 say?

Article 5 says an armed attack on one or more parties in Europe or North America is an attack on them all. Each party then agrees to assist the party attacked.

It will take “such action as it deems necessary, including the use of armed force”. The aim is to restore and maintain the security of the North Atlantic area.

Does every member have to send troops?

No. NATO says the assistance may or may not involve the use of armed force. It can include any action that Allies deem necessary.

So each member judges its own response. The duty to help is shared. The form of help is chosen by each member.

Article 5 is linked to Article 51 of the UN Charter. That article recognises the right of individual or collective self-defence.

Where does Article 5 apply?

Article 6 explains what counts as an armed attack for this purpose. It includes an attack on the territory of the parties in Europe or North America. It also includes an attack on the territory of Türkiye.

It covers islands under the jurisdiction of the parties in the North Atlantic area north of the Tropic of Cancer.

Has Article 5 ever been invoked?

NATO says it invoked Article 5 for the first and only time after the 9/11 attacks on the United States (page updated 12 November 2025).

On 12 September 2001 the North Atlantic Council agreed that an attack directed from abroad would be covered by Article 5. On 2 October 2001 the Council determined that the attacks were regarded as an action covered by Article 5.

Article 4 is the consultation clause. This card shows what it says and the cases NATO lists.

What does Article 4 say?

Article 4 says the parties “will consult together”. This applies whenever, in the opinion of any of them, the territorial integrity, political independence or security of any party is threatened.

An Ally can bring a matter to the North Atlantic Council under Article 4. The issue is discussed there and can lead to a joint decision or action.

When has it been invoked?

NATO’s page, updated 23 September 2025, says Article 4 has been invoked nine times since 1949.

• 10 February 2003: Türkiye asked for talks on defensive assistance, over a threat linked to the conflict in neighbouring Iraq. This is the earliest case on the list.
• 24 February 2022: Bulgaria, Czechia, Estonia, Latvia, Lithuania, Poland, Romania and Slovakia asked for talks after Russia’s full-scale invasion of Ukraine.
• 10 September 2025: Poland asked for talks after multiple Russian drones violated its airspace.
• 23 September 2025: the Council met after Estonia’s request. Three Russian fighter jets had violated Estonian airspace on 19 September.

NATO acts by agreement, not by majority vote. This card shows who decides, who chairs, and where the headquarters is.

Who decides?

All decisions at NATO are taken by consensus. A NATO decision is therefore the expression of the collective will of all 32 member countries (NATO page, as at 9 October 2026).

The North Atlantic Council is the principal political decision-making body. Each member has a seat. It meets at least once a week or whenever the need arises.

Article 9 of the treaty set up this Council. Summits are meetings of the Council at its highest level, with Heads of State and Government.

Who is the Secretary General?

The Secretary General is nominated by member governments for an initial period of four years. The term can be extended by mutual consent.

The post is held by Mark Rutte, the former Dutch Prime Minister. He took up his responsibilities on 1 October 2024.

Where is the headquarters, and what happened in 1966?

In March 1966, France announced its intention to withdraw from NATO’s integrated military command structure. It asked for all Allied headquarters to leave French territory.

NATO HQ moved to Brussels in October 1967. France remained within the Alliance.

NATO counts ten rounds of enlargement since 1949. This card gives each round and the Finland and Sweden story.

What were the ten rounds?

NATO says its membership has grown from 12 to 32 countries through 10 rounds of enlargement (page updated 3 October 2024).

The reunification of Germany in October 1990 brought the territory of the former East Germany into the Alliance.

Why did Finland and Sweden join?

Russia began its full-scale invasion of Ukraine in February 2022. In May 2022, Finland and Sweden declared their intent to join NATO. They presented their applications together.

On 5 July 2022, Allies signed the Accession Protocols. Each Ally then ratified them under its national procedures.

Finland joined on 4 April 2023. Sweden became a full member on 7 March 2024, when NATO counted 32 countries. That makes Finland the 31st member and Sweden the 32nd.

Joining needs every member to agree. This card shows the treaty rule, the steps, and the Sweden case.

What does Article 10 say?

Article 10 says the parties may, by unanimous agreement, invite another European State to accede. The State must be:

• “in a position to further the principles of this Treaty and to contribute to the security of the North Atlantic area”.

A State joins by depositing its instrument of accession with the Government of the United States. Sweden did this in Washington on 7 March 2024.

Because the invitation needs unanimity, one member can block it.

What steps did Finland and Sweden follow?

1. They declared their intent to join and presented their applications.
2. They completed accession talks at NATO Headquarters in Brussels on 4 July 2022.
3. Allies signed the Accession Protocols on 5 July 2022.
4. Allies ratified the protocols under their national procedures.
5. Each country joined the Alliance: Finland on 4 April 2023 and Sweden on 7 March 2024.

The Membership Action Plan was launched at the 1999 Washington Summit. It helps aspirant countries prepare for possible membership.

At Bucharest in April 2008, Allied leaders agreed that Georgia and Ukraine will one day become members. NATO’s page says three partner countries have declared aspirations to membership: Bosnia and Herzegovina, Georgia and Ukraine (page updated 3 October 2024).

Why was Sweden’s entry delayed?

On 28 June 2022, Türkiye, Finland and Sweden agreed a trilateral memorandum in Madrid. NATO said it addressed Türkiye’s legitimate security concerns. It paved the way for Finland and Sweden’s membership.

Hungary’s parliament approved Sweden’s accession by 188 votes to 6 on 26 February 2024. Al Jazeera (news) reported that Hungary was the last Ally to approve. It said Türkiye had ratified the month before.

Which European states stay outside by choice?

Austria’s constitution has included perpetual neutrality since a federal law adopted on 26 October 1955 (University of Graz). Neutral means not joining a military alliance.

Serbia is pursuing EU membership but, NATO says, does not aspire to join the Alliance. NATO says it “fully respects Serbia’s policy of military neutrality”. Serbia joined the Partnership for Peace in 2006.

In 2014 Allies agreed on 2% of GDP. In 2025 they agreed on 5% by 2035. This card shows both decisions and the numbers.

What did Wales decide in 2014?

At the 2014 Wales Summit, Allied leaders agreed to commit 2% of national GDP to defence. NATO says this responded to Russia’s annexation of Crimea.

Wales also set a guideline of at least 20% of defence spending on major equipment.

What did The Hague decide in 2025?

The Hague Summit was held on 24-25 June 2025. Allies committed to invest 5% of GDP annually on defence and security-related spending by 2035.

Allies agreed to submit annual plans showing a credible, incremental path to 3.5%. The balance of spending will be reviewed in 2029.

The Hague text ties the pledge to Article 3 of the Washington Treaty. It lets direct contributions to Ukraine’s defence count when calculating Allies’ defence spending.

What do the numbers show so far?

NATO’s page (updated 29 June 2026) says European Allies and Canada raised defence spending in 2025 by over USD 90 billion in 2021 prices. In nominal terms that is close to USD 139 billion.

These are two ways of stating one increase, not two increases. Their combined spending rose from 1.4% of GDP in 2014 to 2.3% in 2025.

The latest summit was held in Türkiye in July 2026. This card gives the main points from the declaration and the Secretary General.

What did the leaders say?

The 2026 summit was held in Ankara, Türkiye, on 7-8 July 2026. The Ankara Summit Declaration is dated 8 July 2026.

• Article 5: leaders reaffirmed their “ironclad commitment” to collective defence under Article 5.
• The Hague pledge: the declaration says Allies are delivering on The Hague defence commitment.
• Procurement: Allies announced more than USD 50 billion in new procurements.
• Ukraine: for 2026, Allies pledged EUR 70 billion in military equipment, assistance and training. They affirmed at least equivalent levels in 2027.
• Iran: the declaration calls on Iran to respect freedom of navigation in the Strait of Hormuz.

The declaration gives the procurement figure in dollars. The Secretary General’s article gives it as over EUR 50 billion. This lesson uses the declaration’s USD figure.

What did the Secretary General add?

Mark Rutte said total defence and security spending was already around 4% one year into the 10-year effort (8 July 2026).

He also announced a EUR 27 billion investment to enhance NATO’s fuel supply chain.

Where will leaders meet next?

The Hague Declaration said Allies look forward to their next meeting in Türkiye in 2026, followed by a meeting in Albania. The text names only Albania, not a city or a date.

India is not a NATO member. This card shows what NATO’s own page says, and what news reports say India has said.

Is India a member or a partner?

India is not a member. NATO has a number of “global partners” that it cooperates with individually. Its page says they include Australia, Japan, the Republic of Korea and New Zealand.

India is not named in that list (page updated 3 October 2024).

The same page says NATO also consults non-member countries that have no bilateral programme of cooperation. It gives China, Brazil, Ghana, India and Singapore as examples.

What has India said? (news reports)

India TV (news) reported on 8 June 2023 that External Affairs Minister S. Jaishankar rejected joining NATO Plus. He said the “NATO template doesn’t apply to India”.

The same report says a US congressional committee had recommended strengthening NATO Plus by including India. It describes NATO Plus as NATO and five aligned nations: Australia, New Zealand, Japan, Israel and South Korea.

ThePrint (news) reported in July 2025 that Mark Rutte warned Brazil, India and China of secondary sanctions over Russian energy purchases. It reported that MEA spokesperson Randhir Jaiswal replied on 17 July 2025. He cautioned “against any double standards”.

These two items rest on one news report each. Treat them as press accounts, not official texts.

The 2025 Prelims paper asked how many of six countries are NATO members. This card shows the question, the count and the traps.

Which question was it?

What does NATO’s list give?

NATO’s enlargement page gives accession dates for four of the six. Counting from those dates gives “Only four”. The official UPSC key for Series A agrees: (b).

What are the traps?

1. Neutral is not a member. Austria’s neutrality is in its constitution, and it is not a NATO member.
2. Partner is not a member. Serbia joined the Partnership for Peace in 2006 but does not aspire to join NATO.
3. Newest member. Sweden is the 32nd (7 March 2024). Finland is the 31st (4 April 2023).
4. Signed is not in force. The treaty was signed on 4 April 1949. It came into force on 24 August 1949.
5. Article 5 is not automatic troops. Each member picks its own action.
6. Article 4 is not Article 5. NATO says Article 4 has been invoked nine times (as at 23 September 2025) and Article 5 once.
7. The 5% has two parts. At least 3.5% is for core defence and up to 1.5% is for resilience and related spending.
8. India is not a member or a named global partner. NATO’s partners page does not name it.