Sweden has officially become the 32nd member of Nato, Prime Minister Ulf Kristersson has confirmed.
PM Kristersson handed over the final documentation to the US government, the last step in the process to secure the backing of all members to join the military alliance.
US Secretary of State Antony Blinken said: "Good things come to those who wait...This is a historic moment for Sweden, for our alliance and for the transatlantic relationship."
For Nato, the accessions of Sweden and Finland, which share a 1,340 km border with Russia, are the most significant additions in decades. It is also a blow for Russian President Vladimir Putin who has sought to prevent any further strengthening of the alliance.
Prime Minister Ulf Kristersson handed documentation to US Secretary of State Antony Blinken
Reuters
Sweden will benefit from the alliance's common defence guarantee under which an attack on one member is regarded as an attack on all.
Blinken added: "The reason this is such a strong, powerful fit, is because Sweden embodies and promotes the core values that are at the core of Nato- democracy, liberty, the rule of law."
PM Kristersson said: "Unity and solidarity will be Sweden's guiding lights as a Nato member. We will share burdens, responsibilities and risks with our allies."
"We will defend freedom together with the countries closest to us – both in terms of geography, culture and values."
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Prime Minister of Sweden Ulf Kristersson
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While Stockholm has been drawing ever closer to Nato over the last two decades, membership marks a clear break with the past, when for more than 200 years, Sweden avoided military alliances and adopted a neutral stance in times of war.
After World War Two, it built an international reputation as a champion of human rights, and since the Soviet Union collapsed in 1991, successive governments have pared back military spending.
Researcher at defence think tank SIPRI Barbara Kunz said: "Joining NATO is really like buying insurance, at least as long as the United States is actually willing to be the insurance provider."
Carl Fredrik Aspegren, 28, a student in Stockholm said: "I guess [Sweden] had to take a stance really and I'm happy that we actually did and that we are safeguarded by Nato, because the tension with Russia has been growing for a couple of years."
U.S. Secretary of State Antony Blinken accepts Sweden's instruments of accession from Sweden's Prime Minister Ulf Kristersson, alongside Sweden's Minister for Foreign Affairs Tobias Billstrom
Reuters
Hakan Yucel, 54, an IT worker in the Swedish capital said of the announcement: "Before, we were outside and felt a little bit alone...I think that the threat from Russia, it's going to be much less now."
Russia's invasion of Ukraine forced Nato to rethink its national security policy and conclude that support for the alliance was the Scandinavian nation's best guarantee of safety.