Sweden's idyllic Gotland island could become a strategic 'watchtower' in the north to keep an eye on Vladimir Putin.

Ottilia Soderstrom has lived on Gotland, Sweden's largest island, since moving here about a year ago with her family in pursuit of peaceful life and great kitesurfing conditions after years spent abroad.

"It's one of the best places I've ever surfed in the world and it's one of the best places to learn with gentle winds and shallow bays," says her partner Floyd Paul, who runs a kitesurfing school.

But the ripples of Russia's war in Ukraine have reached their shores.

They now face an unexpected reality, as their backyard is transformed into an "Unsinkable aircraft carrier", or what others describe as the "Watchtower of the north". 

"The nature is so peaceful and feels so untouched… so when I drove down the road the other day and I could see weapons, and military, it gave me shivers," Ottilia says.

Their afternoon biking trail is now cut with deep tank tracks. 

The invasion of Ukraine has led to historic changes in their community and country. 

Gotland is being remilitarised in case it is called upon to uphold security and order in northern Europe, as Sweden abandons centuries of war-time neutrality in applying to join the North Atlantic Treaty Organisation (NATO).

The country's membership bid, along with Finland's, is set to be discussed this week at an important NATO summit — but not everyone is convinced. 

Many Swedes, like Ottilia, see neutrality and peace as a core part of their country's identity.

"I think we need to focus on peace negotiations, rather than arming up, because what is going to happen in response to this? We don't know,"  Ottilia says.

"I really question how this has all happened so quickly… and it's not what I want for my son."

The Swedish officials willing to make this historic shift have challenges ahead too — not just to convince the public, but to persuade some member states to let them into the security bloc. 

Gotland to become a 'watchtower' for northern Europe:

The expansive shorelines and shallow coastal waters that attracted Ottilia, Floyd and their son Willow to Gotland are what also make it the perfect military base. 

It has a strategic position in the middle of Baltic Sea — only about 350 kilometres from Russia's navy base in the enclave of Kaliningrad. 

"The country that controls Gotland can control a lot of the air and sea movements in the Baltic Sea," Colonel Magnus Frykvall (Below) says.

He is the man in charge of ramping up defences here, the new commander of the Gotland Regiment.

"People often say that Gotland is the aircraft carrier that you can't sink, but yes you could also probably call it [the watchtower of the north]," he says. 

The Baltic Sea is one of the key trading routes in Europe, providing a gateway from the north-east to central parts of the continent. 

"The Baltic Sea has 15% of the world cargo and maritime cargo trade — so it is fairly significant," says Professor Kjell Englebrecht, dean of the Swedish Defence University.

"It is also critical to Russia — it has its commercial ports in the Finnish Bay, a very important naval base in Kaliningrad, so if you take a broader perspective, then certainly this area is very important to European security." 

If Sweden and Finland join NATO, it means all countries, except Russia, that border the Baltic Sea would form one defence bloc, providing security to not just northern Europe but the whole continent.

"It's going to shore up the defence posture of the alliance in this part of Europe… it becomes one operational theatre," Professor Engelbrecht says. 

"If the Russian armed forces are planning to engage or capture part of a Baltic country, then certainly we will be able to disrupt that… although I don't think there's an imminent threat."

Sweden has long used Gotland to ensure security for themselves and their partners. 

Through the Cold War, the island had four regiments of almost 25,000 soldiers, but its numbers shrank over subsequent decades and the units were fully disbanded in 2005. 

But the invasion of Ukraine in February this year changed everything for Sweden, where the threat of Russia always looms large. 

"The judgement was that we need to increase the capability on the island as fast as possible," Colonel Frykvall says. 

There has been a slow ramping up of infrastructure, personnel and hardware since 2018, in part due to Russia's invasion in eastern Ukraine, Colonel Frykvall says. 

He is trying to build a force of 4,000 war-ready personnel in as little as a year. 

"We will have the capability that we need to ensure that the threshold for an aggressor to attack Gotland will be so high that they would probably choose to not do that," he says.

He hopes to see another extra line of defence soon — membership in NATO. 

The roadblock to Sweden's NATO bid:

Sweden's application will be discussed at summit of NATO leaders in Madrid this week, but despite promises of quick accession, both Finland and Sweden have hit a speed bump.

Turkey, a current NATO member, has vowed to block the application for both Nordic nations. 

Turkish President Tayyip Erdogan has taken issue with both countries' stance on Kurdish political groups, accusing them of harbouring "Terrorists", and criticised their decisions to ban arms exports to Turkey over its actions in Syria. 

"I was always warning people that there were a couple of stumbling blocks on the path towards ratification," Professor Engelbrecht says.

"Part of it seems to be about the activism of Kurdish exile groups in Sweden; we can't do much about [that] because we have rule of law, we have a constitution, we need to respect the political rights of these groups. 

"Some political parties have also engaged with these groups and that may perhaps be something that the Turks would want those parties to step back from. 

"I think it may be more a way for Turkey to put pressure on the Europeans and perhaps on the Americans to rein in some of their arms export controls. 

"We may just be kind of a pawn in that game with Brussels and Washington."

He is confident that the NATO application will ultimately be successful. 

"It's impossible to know… but I think by the end of the year, these negotiations will carry on but then be concluded."

The diplomatic dance looks likely to cause some headaches at home, with the NATO move already agonising some Swedes. 

NATO decision divides Swedes:

Matthias Anderson and Calle Ewald (Above) are business partners, friends and staunchly divided about their country's choice to join NATO. 

They sit side by side at a table of their surf lodge in Tofta, built on a sand dune on the Gotland coastline.

They have built their business on the idea of peace, relaxation and isolation. 

"Ten years ago, I would say, 'Hey, no, we haven't been in a war for 200 years, why should we move into a group of alliance that uses nuclear weapons and be a part of that?'" Calle says. 

"But as it is now, there is a need for it, it's a no-brainer." 

Matthias is not convinced by the values of the alliance — nor the way this application has transpired.

"I think it's essentially it's a slap in the face to the Swedish democracy, because we elected the government who's now currently in power, and they have always historically been against NATO," he says. 

"We have a vote later on this year where they could go in and say, 'Hey, vote for us and we'll join NATO' and then actually the electorates would be able to have a word." 

The two descend into a tense but thoughtful conversation about the future of their island and the nation.

At one strained moment Calle quips to his friend: "Check your facts, darling." 

Matthias shrugs defiantly: "I am probably in the minority and Calle the majority."

A poll conducted by a Swedish newspaper in April found 57% of Swedes supported joining NATO, up from 51% in March. 

Both men grew up on the island in the 80s when a military base was still operating from the Cold War era. 

But the only barricades and fortresses their children have known on the island are the old ancient Viking structures in town that attracts thousands of visitors.

"I grew up here with military field close by, so we're kind of used to [it] and I don't really think it will affect us or the tourism industry so much," Calle says.

Matthias shakes his head. While he agrees the local tourism industry will probably be OK, he would prefer not to see the island become a modern-day defence base.

"I don't think it's good to normalise war, and I don't think it's good for my children to see people walking around with weapons [made for] killing other people, because that makes it normal for them," Matthias says.

Story By | Isabella Higgins in Gotland