Nato Secretary-General Jens Stoltenberg responded to Russian President Vladimir Putin's comments on possible increased Nato military presence in Finland and Sweden during a press conference which concluded the alliance's summit in Madrid.

"Finland and Sweden are sovereign nations, and they have the right to choose their own path and join Nato. We have welcomed them into our alliance and we are of course prepared for any eventuality," Stoltenberg said, adding that Russia's stance on the Nordic countries joining the alliance has been quite mixed.

"They have communicated different messages from Moscow on that issue," he stated.

Undeterred by smoke screens and signals from Russia, Stoltenberg reiterated what was vital for the alliance.

"The most important thing is that Finland and Sweden will become members," he said.

Finland's next Nato steps

Following the issuing of the invitation to join, Finnish President Sauli Niinistö said that Finland's Nato accession protocol will be signed next week, and this was confirmed by Stoltenberg.

"We will do the formal signing of the accession protocol on Tuesday with Finnish and Swedish foreign ministers," Stoltenberg said.

Finnish foreign minister Pekka Haavisto (Green) told Yle that accession negotiations will likely take place on Monday. This step will make sure Finland and Sweden fulfil Nato's political, economic, and military requirements prior to the accession protocol.

After signing the protocol, the two Nordic nations will become observer members. This means a closer coexistence with Nato than before, said Tuomas Forsberg, head of the University of Helsinki's Research Council on Yle TV1's breakfast show.

"We'll start to be even closer at [Nato] meetings. Even at the official level, the cooperation with the soldiers will become closer when we move towards membership, whenever that happens," said Forsberg.

He added that the accession protocol is a relatively simple document, but the ratification of Finland and Sweden's membership by the member state legislatures can take an unpredictable amount of time.

"It is possible that, for example, Turkey can still block membership, but it is considered likely that this too would be resolved one way or another," Forsberg said.

However, German Chancellor Olaf Scholz told reporters in Madrid that Germany will begin ratifying Finland and Sweden's accession this week. Other member states have taken similar steps already, although this parliamentary process is expected to last up to a year.