Nato Secretary General Jens Stoltenberg urged western allies to stick together as the organisation marked its 75th anniversary on Thursday with a series of commemoration events.
The bloc gathered in Brussels this week for a two-day meeting where they discussed Russia's aggression on its borders and the spectre of Donald Trump's return to the White House.
The outgoing Nato leader, who will step down this year, extolled the benefits of the alliance in his speech, saying the US and Europe's militaries need to work together in the face of external threats and the war in Ukraine.
“I don't believe in America alone, just as I don't believe in Europe alone. I believe in America and Europe together in Nato because we are stronger and safer together,” Mr Stoltenberg said at a ceremony at Nato headquarters in the Belgian capital.
He added that European allies provide world-class militaries, “vast” intelligence networks and diplomatic leverage that have helped to “multiply America's might”.
On Thursday, Mr Stoltenberg oversaw a solemn wreath-laying ceremony as well as a cake-cutting event alongside Belgium's Foreign Minister Hadja Lahbib. A bigger celebration is expected to take place at a summit in Washington in July.
President Joe Biden hailed Nato as “the greatest military alliance in the history of the world” in a statement that paid tribute to allies that were pushing back against aggression, including decisions to increase their annual defence spending by almost $80 billion.
“We must remember that the sacred commitment we make to our Allies — to defend every inch of Nato territory — makes us safer too, and gives the United States a bulwark of security unrivaled by any other nation in the world."
Nato's founding treaty was signed in 1949 by members from North America and Europe in response to growing fears that the Soviet Union posed a military threat to Europe.
Since then, Nato – the North Atlantic Treaty Organisation – has grown from 12 to 32 countries. Its expansion has greatly angered Moscow which used it as its justification for invading Ukraine, provoking a new Cold War.
The alliance also faces threats ranging from terrorist groups to hybrid operations, which combine military and non-military tactics, and a frontier in space. The election of Donald Trump, a fierce critic of Nato, could also destabilise the alliance.
The bloc's hopes include a push for influence beyond its geographical home ground into the Middle East and North Africa, with the war in Gaza serving as further evidence of the importance of regional influence.
Russia, already fighting a war in Ukraine, potentially has other ambitions to expand. Georgia has two troubled regions, South Ossetia and Abkhazia, that border Russia. Moldova has for decades faced pro-Moscow separatism in Transnistria.
Russian President Vladimir Putin has ruled out a direct attack on Nato countries that used to be under Soviet influence, but nations such as Poland remain wary.
British Foreign Secretary David Cameron said Nato's future success depends on showing future generations that it overcame the threat that Ukraine faces from Russia.
Lord Cameron said he grew up believing in the alliance because he saw “the importance of the solidarity” it offered nations. However, he added, that appreciation is no longer universal.
“Future generations who haven't grown up with that knowledge, but have grown up in a different situation – I think we have to win the argument for Nato all over again,” he said.
Ukrainian Foreign Minister Dmytro Kuleba, who attended a meeting of the NATO-Ukraine Council, highlighted the threat his country and the wider alliance faces from Moscow. “I didn’t want to spoil the birthday party for Nato, but I felt compelled to deliver a sobering message on behalf of Ukrainians about the state of Russian air attacks on my country, destroying our energy system, our economy, killing civilians," Mr Kuleba, who attended a meeting of the NATO-Ukraine Council, said.
Adversaries
“Despite the anniversary, there is nothing to celebrate,” Russian Foreign Ministry spokeswoman Maria Zakharova said on Wednesday.
“Today, in relations with Russia, the bloc has returned to Cold War settings.”
Mr Putin announced the full-scale Russian invasion of Ukraine in February 2022, saying that Moscow's aim was to “de-Nazify” its neighbouring country.
But Russia is not the only challenge facing Nato.
In February this year, Beijing said it wanted to be a “force for stability” in addressing global hotspot issues in a “Chinese way”.
Foreign Minister Wang Yi said China “advocates for non-interference in internal affairs and opposes imposing one’s will on others”.
North Korea, Iran and other regional powers also challenge Nato. The bloc in November last year condemned Pyongyang's launch of a military satellite as “reckless”.
Nato is also wary of Iran’s nuclear programme and its support for Russia in Ukraine.
“Tehran’s offensive military posture and nuclear ambitions are drivers of tension, while its direct support for Russia’s war against Ukraine further underlines the challenge it poses to euro-Atlantic security,” a Nato report said.
Hostile forces
Hybrid warfare, including propaganda and deception, have long been used to contest the alliance's reputation within its member states and third countries.
“What is new about attacks seen in recent years is their speed, scale and intensity, facilitated by rapid technological change and global interconnectivity,” the Nato report said.
As climate change gathers momentum, population displacement and resource scarcity could become even greater problems than they are today.
But despite the vast array of concerns, terrorism remains the biggest day-to-day threat facing people across the bloc.
“Terrorism is the most direct asymmetric threat to the security of the citizens of Nato countries, and to international stability and prosperity,” the Nato report said.
“A persistent global issue that knows no border, nationality or religion, terrorism is a challenge that the international community must tackle together.”
Article 5 of the North Atlantic Treaty, which states that an attack on one member state is considered an attack on the bloc as a whole, was invoked for the first time in 2001 after the 9/11 terror attacks in the US.
When the Cold War ended with the Soviet Union's collapse, countries that had previously been under Moscow's influence began to seek membership of the alliance. Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia and Slovenia were all added to the bloc.
After Russia's invasion of Ukraine, the bloc gained two more members – Finland, which joined last year, and Sweden, whose accession was confirmed last month.
