They announced the start of talks for Norway to join the group of countries coming under France’s nuclear protection — that is, the French nuclear umbrella.

The plan already includes Germany, Poland, the Netherlands, Belgium, Greece, Sweden, Denmark and the UK. The UK is the only other European country with a nuclear arsenal, and it joined as a way to coordinate its deterrent with its closest neighbour.

France says Europe needs to take greater responsibility for its own security, amid growing concerns over the commitment of the United States to Europe’s defence.

For many years French nuclear weapons were exclusively linked to France’s own security. France is now opening up dialogue with close allies on how its nuclear weapons can also contribute to European security and deterrence against military threats. Norway wants to be part of that dialogue, alongside its Nordic neighbours and partners like the UK, Germany and Poland.

Norway is the European country closest to the largest nuclear arsenal in the world — Russia’s, in the Kola Peninsula, just 60 miles from Norway. The issue is therefore very sensitive there: Norway has not wanted a nuclear profile, which is why it took longer to sign up.

There are worries that US nuclear capability — which has been the backstop of NATO’s security guarantees since the alliance began — is no longer so certain, with allies unsure whether the Americans would really come to the defence of a European ally in case of attack. Norway is therefore worried about the threat in both directions.

It does not involve hosting nuclear weapons — Norwegian legislation says Norway will not host nuclear weapons, and the Prime Minister was clear that does not change. None of the European countries signed up to the deterrence initiative want to host them. This contrasts with the NATO nuclear umbrella, under which US nuclear weapons are pre-positioned in several European countries.

France will temporarily deploy nuclear-capable aircraft to some of these countries, so they would be ready to move in case of a nuclear incident or attack. They will also increase exercises and coordinate more intelligence. This is a major shift because, until now, France’s nuclear deterrent sat alone — it was not extended to other countries. President Macron announced this change on 2 March.

She says the US has actively been trying to give away its security influence — it wants Europe to become more self-sufficient. Norway is interesting because it is one of the most pro-US countries in NATO and has always called the US its most important security partner (as has Denmark, which also joined). So Norway’s move represents a real change of tone, although the US would only welcome Europe being more self-sufficient.

All the conversations — on the record and off the record — say that the US has not put into question its nuclear guarantees for Europe. So although there is concern about American reliability, Washington has not formally withdrawn its nuclear commitment.

Russia has not reacted to the Norwegian announcement, but when the French initiative was first made in early March, Russia said any country willing to host nuclear-capable aircraft would itself become a target. The correspondent says this is de rigueur for the Russian government — they say it about any European move to boost security — so it’s not surprising, and the countries involved do not see it as an imminent threat.

Norway has said that it sees Russia boosting its nuclear arsenal, even while tied up in Ukraine. It is very concerned that Russia may be preparing to test NATO’s will when it comes to nuclear weapons and a potential nuclear attack.