In a summit statement, the leaders said they consider that attacks to, from, or within space could be a challenge to NATO that threatens national and Euro-Atlantic prosperity, security, and stability, and could be as harmful to modern societies as a conventional attack.Such attacks could lead to the invocation of Article 5.

NATO leaders on Monday expanded the use of their all for one, one for all, mutual defence clause to include a collective response to attacks in space.

Article 5 of NATO's founding treaty states that an attack on any one of the 30 allies will be considered an attack on them all. Until now, it's only applied to more traditional military attacks on land, sea, or in the air, and more recently in cyberspace.

“Such attacks could lead to the invocation of Article 5. A decision as to when such attacks would lead to the invocation of Article 5 would be taken by the North Atlantic Council on a case-by-case basis,” they said.

Around 2,000 satellites orbit the earth, over half operated by NATO countries, ensuring everything from mobile phone and banking services to weather forecasts. Military commanders rely on some of them to navigate, communicate, share intelligence and detect missile launches.

In December 2019, NATO leaders declared space to be the alliance's “fifth domain” of operations, after land, sea, air and cyberspace. Many member countries are concerned about what they say is increasingly aggressive behavior in space by China and Russia.

Around 80 countries have satellites, and private companies are moving in, too. In the 1980s, just a fraction of NATO's communications was via satellite. Today, it's at least 40%. During the Cold War, NATO had more than 20 stations, but new technologies mean the world's biggest security organisation can double its coverage with a fifth of that number.

NATO's collective defence clause has only been activated once, when the members rallied behind the United States following the September 11, 2001, attacks.

Former President Donald Trump raised deep concern among US allies, notably those bordering Russia like Estonia, Latvia, Lithuania and Poland, when he suggested that he might not rally to their side if they didn't boost their defence budgets.

President Joe Biden has been trying to reassure them since taking office and has used the summit, his first at NATO, as a formal opportunity to underline America's commitment to its European allies and Canada.

Biden said Monday that Article 5 is “a sacred obligation” among allies. “I just want all of Europe to know that the United States is there,'' he said. ''The United States is there.”