Finland and Sweden intending to join Nato is not just a radical departure from decades of Nordic foreign policy, it also shows how the invasion of Ukraine has altered the political landscape in Europe - not just in Scandinavia.

There was a time when many left-leaning politicians in Europe viewed everything related to defence and security alliances with suspicion. Their anti-militarism and pacifism then sometimes merged with a broader anti-American sentiment, especially under US Presidents such as George W Bush and Donald Trump.

Putin’s war has changed such pacifist reflexes.

Perhaps it is no surprise the European left has exhibited a greater resolve and clarity towards Ukraine than many right-wing politicians. That is because many on the progressive side of politics see the brutal aggression against a peaceful, democratic country as what it is: a moral issue, not a business matter.

Finland’s prime minister, Sanna Marin, illustrates this shift in attitude. She was 34 when she became prime minister in 2019. In her 20s, she served as president of the Social Democratic Youth Association and campaigned against fur farming, income inequality, and the pharmaceutical industry.

When she entered parliament in 2015, Marin opposed nuclear power, rejected Nato, and focused on climate change. Commentators located her on the left-wing of the Finnish Social Democratic Party.

There was no sign Marin would lead her country into Nato, which she had so vehemently rejected earlier, yet now she leads the effort to end more than seven decades of Finnish neutrality. Even before the invasion of February 24, Marin had been one of the most vocal European politicians criticising Putin and supporting Ukraine.

Across the border, in Sweden, it is a similar story. Like Finland, Sweden is also governed by a centre-left government, led by Prime Minister Magdalena Andersson since November 2021.

Shortly after taking office, Andersson said in an interview that Covid “marks the end of the era of neoliberalism which was established under Thatcher and Reagan”. She outlined her ambitions: “Going forward, we’re going to realise that we need more politics, more collective solutions. My expectation is that the 2020s will be a decade where there is a growing call for collective solutions. This is a paradigm shift.”

It is not without irony that Andersson is now following in the footsteps of Thatcher and Reagan, if not on the economy, then on defence and armament. Sweden, too, is aspiring to join Nato, which would mark the end of an even longer policy of neutrality than Finland's.

With Sweden and Finland joining, all Nordic countries will soon be Nato members (Denmark, Norway and Iceland were founding members in 1949). It is a significant shift, happening at a time when all five countries are led by centre-left parties.

These Nordic developments are historic, but the changes on the left of the German political spectrum are perhaps even more striking. In Germany, it is the Greens who are most in favour of Nato and defence spending these days.

Unlike their Scandinavian comrades, Germany’s social democrats are struggling to adjust to the new security landscape. Going back to the Cold War, the SPD always maintained good relations with Moscow. Social Democrats also worked with Putin’s regime on gas exports in recent decades - so much so that former German Chancellor Gerhard Schröder even became a highly paid Gazprom lobbyist.

The German Greens, however, are not compromised in these ways. They have cultivated a long tradition of engagement with civil society institutions in Eastern Europe and Russia. Promoting liberal democracy was their primary concern, not achieving economic gains.

Their party foundation, the Heinrich Böll-Stiftung, demonstrates the Greens’ focus on Eastern Europe. Although a minor party, the foundation has built a remarkably strong presence in the region with offices in Sarajevo, Belgrade, Tbilisi, Kyiv and Moscow. Evidently, the Kremlin has noticed the Greens’ engagement too. It revoked the foundation’s registration and closed its Moscow office.

The Greens are one of three coalition partners in the government of Germany. Former female co-leader Annalena Baerbock is the foreign minister, while her male counterpart, Robert Habeck, is the economy and energy minister. Following the invasion of Ukraine, their ministries have become crucial, and Baerbock and Habeck are prominent in the German government.

Habeck publicly advocated sending arms to Ukraine almost a year before the war. He is now fast-tracking any applications for weapons deliveries as a minister. At the same time, he is managing a transition away from Germany’s reliance on Russian energy.

Baerbock, meanwhile, has visited Ukraine several times since becoming foreign minister late last year. She is also the first German cabinet minister to visit Ukraine during the war, while the social democrat chancellor, Olaf Scholz, appears timid and indecisive.

Since the Greens’ roots are in pacifism, their transformation into a party at ease with military engagement is all the more remarkable. They were formed in the late 1970s in opposition to Nato’s deployment of medium-range nuclear weapons in Western Europe, the so-called Nato Double-Track Decision.

Four decades later, the German news magazine Der Spiegel features prominent Green politicians on its cover dressed in camouflage gear under the headline “Die Olivgrünen” (“The olive-Greens”).

It would be all too easy to dismiss all these developments as a remilitarisation of European politics. And no, it isn’t a return of the Cold War with its anti-communism, either.

The main reason this time is different is because the new focus on defence and military alliances is not driven by conservatives. It is politicians such as Sanna Marin, Magdalena Andersson, Annalena Baerbock and Robert Habeck who are leading Europe’s security reorientation. They do so from the premise of protecting and promoting liberal and democratic values, at home and abroad. And they are happy to do so under the umbrella of Nato.

Incidentally, that is exactly what Nato was established to do. With its focus on “the principles of democracy, individual liberty and the rule of law”, this is precisely what the Nato Treaty spelt out in its preamble. Though it was written in 1949, today’s centre-left will have no problem going along with the goals of that treaty.

Maybe it is fortunate for Europe that some centre-left and Green politicians are at the helm in this time of crisis. These are politicians who put their values and democratic principles above short-term (and short-sighted) economic interests. And they are politicians who realise that liberal democracy must defend itself against external threats, particularly those posed by autocracies.

Of all the developments triggered by Putin’s war, this may be the most surprising one. It will be interesting to see whether only the left in Europe will focus on security in this way.