Newspapers in Sweden and Finland have reported its respective governments have agreed to submit NATO applications at the same time. They said the joint submissions will happen in the middle of May.
Finnish newspaper Iltalehti said the Swedish government has expressed a wish to Finland that the two nations apply together in the week starting May 22.
Swedish government sources confirmed the information to Sweden’s Expressen tabloid.
According to the outlets, Russia’s invasion of Ukraine has led to growing support in Sweden and Finland for joining NATO.
Though currently not members, both Nordic countries already closely co-operate with NATO, allowing the alliance’s troops to carry out exercises on its borders.
Helsinki and Stockholm has also substantially intensified its bilateral defence co-operation in recent years.
Sweden previously signalled its intention to apply for NATO membership on April 13, in a move which infuriated Moscow lawmakers.
Sources told Sweden’s SVD newspaper about the move on the same day Finland started its debate on joining NATO after days of speculation it would do so.
Sweden’s prime minister Magdalena Andersson is understood to be eager for the country to join the trans-Atlantic alliance by June.
Finland is similarly hoping to start its application process “within weeks, not within months”, its prime minister Sanna Marin said on April 13.
The Swedish application was previously expected to be submitted by the NATO meeting in Madrid on June 20 to June 29, according to Swedish reports earlier this month.
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Both Sweden and Finland historically avoided NATO membership, despite close alignment with the West, in an effort not to provoke Russia.
On April 14, Moscow said it will be forced to strengthen its defences in the Baltic if Finland and Sweden join NATO, including deploying nuclear weapons.
The Russian former president Dmitry Medvedev, a senior member of Russia’s security council, said: “Naturally, we will have to reinforce these borders”, by bolstering ground, air and naval defences in the region.
He added Finnish and Swedish NATO membership would mean there could be “no more talk of any nuclear-free status for the Baltic – the balance must be restored”.
Russia had “not taken such measures and was not going to”, he said, adding: “But if our hand is forced, well … take note it wasn’t us who proposed this.”
Alexander Grushko, Russia’s deputy foreign minister, said Moscow would take the security and defence measures that it would deem necessary if Sweden and Finland join NATO.
He added the move would seriously worsen the military situation and lead to “the most undesirable consequences”.
Meanwhile, on Friday Russian state TV host Vladimir Solovyov said Western countries do not have enough weapons to protect themselves if Russia attacks them.
Mr Solovyov said: “I believe the special military operation is entering a new stage.
“Ukrainians alone are no longer enough, now they’re talking about NATO countries supplying de-facto their own weapons.
“We’ll see not only NATO’s weapons being drawn into this but also their operations de-facto.
“We’re starting to wage war against NATO countries, we’ll be grinding up NATO’s war machine.”
Mr Solovyov added: “As well as citizens of NATO countries when the operation concludes, NATO will have to ask itself: do we have what we need to defend ourselves?
“Do we have the people to defend ourselves, and there will be no mercy.
“Not only Ukraine will be de-Nazified, but the war against Europe and the world is also developing a more specific outline.
“Which means we’ll have to act differently and to act much more harshly.”