The Ukraine war is prompting the Nordic country to reconsider an opt-out clause that dates back to the early 1990s.
Russia's invasion of Ukraine appears to be prompting the European Union to drop all of its long-standing taboos about defence, one at a time.
For the first time ever, the bloc is financing the purchase of lethal weapons for countries that are under attack, a decision that European Commission President Ursula von der Leyen has described as a "watershed moment".
Since the EU treaties prevent the common budget from bankrolling military operations, the EU will provide Ukraine with a €500 million fund under an off-budget instrument known as the European Peace Facility.
Meanwhile, Germany has drastically reversed its post-WWII policy that prevented the country from sending lethal weapons to conflict zones and is equipping the Kyiv government with 1,000 anti-tank weapons and 500 anti-aircraft Stinger missiles.
Finland and Sweden, two traditionally non-aligned countries, are also delivering arms to help the Ukrainian army resist the Russian invasion. Even Switzerland, a non-EU member state, is ditching its sacrosanct neutrality to slap painful sanctions on the Kremlin.
"European security and defence has evolved more in the last six days than in the last two decades," von der Leyen told the European Parliament last week, reflecting on the transformative events that followed the Russian attack on 24 February.
Now, another European country is having a change of heart.
The Danish government led by Prime Minister Mette Frederiksen has announced the country will hold a referendum to reconsider the 30-year-old opt-out clause that has so far kept Denmark away from the EU common defence policy.
The referendum will be held on June 1.
Frederiksen also said the government will boost its defence spending to meet NATO's 2% of GDP target by 2033, up from its current 1.44% share. The last time the country surpassed the 2% mark was in 1989.
"Putin's pointless and brutal attack on Ukraine has heralded a new era in Europe, a new reality," Frederiksen said at a press conference in Copenhagen.
"Ukraine's struggle is not just Ukraine's, it's a test of strength for everything we believe in, our values, democracy, human rights, peace and freedom."
A document signed by Frederiksen's Social Democrats alongside four other parties speaks of a "new security situation" that must be confronted "with our allies in NATO and the EU." Besides changes to the country's defence policy, the parties touch upon Europe's heavy reliance on Russian gas.
A tailor-made provision
For Denmark, the U-turn is momentous.
The opt-out clause was introduced at Denmark's behest as part of the 1992 Edinburg Agreement, a text specially designed to allow the Danish country to ratify the 1991 Maastricht Treaty, which Danish citizens had narrowly rejected with 50.7% of voters against.
The agreement proposed tailor-made provisions that clarified Denmark's participation in four new fields where the EU had begun to deepen its integration: citizenship, justice and home affairs, the monetary union (Denmark rebuffed the euro and kept the national krone), and defence.
Today, the opt-out is still in place and applies to the so-called Common Defence and Security Policy (CDSP), one of the main elements of the bloc's Common Foreign and Security Policy (CFSP).
Consequently, Denmark, which is a NATO member, removes itself from all foreign policy decisions that have defence implications. During the in-person meetings of foreign affairs ministers, the Danish representative usually leaves the room when defence topics are broached.
All the remaining 26 member states engage fully in the CDSP.
In practice, this means the Nordic country participates in collective action related to, for example, economic sanctions, as it has been the case against Russia, but stays clear when it comes to military deployments, such as Operation IRINI, created to enforce the United Nations arms embargo on Libya.
These overseas missions are carried out under the leadership and coordination of the EU but their military forces are seconded from member states on a case-by-case basis.
Over 5,000 EU military and civilian staff are currently stationed in CSDP missions across Europe, Africa and Asia, with most of them focused on crisis management. A total of 37 operations have been launched since 2003; almost half of them still ongoing.
If Danish citizens vote to repeal the opt-out clause, the country will become immersed in the common defence policy and Danish troops will be deployed around the world under a centralised command.
So far, the CSDP has been a "technical project," centred on industrial cooperation and procurement rather than on building a proper EU army, a goal still considered divisive and remote, says Bruno Lété, senior fellow at the German Marshall Fund of the United States.
"Europeans have done a bad job thinking about their own defence," Lété tells Euronews.
"In the military response to the Ukraine war, Europe has joined the response. The US was clearly the driver," he adds. "Europeans are now realising that this situation is no longer sustainable."
But the Ukraine war, with its horrors unravelling right at the EU's doorstep, has served as a "wake-up call" for the bloc, leading to a "new dynamic", says Lété. A dynamic where capitals, from Berlin to Copenhagen, rethink their defence strategies and become more aware of the geopolitical environment that surrounds them.
"It's still early to say how this [wake-up call] will develop. Some member states will prioritise NATO structures. Others will argue the EU should be able to lead its own military missions, if needed," the researcher says, noting that NATO will continue to add value "no matter what."
The 2024 presidential election in America might also play a role in boosting the EU's own defence capabilities and pursuit of self-reliance, according to which way the wind blows.
Even if President Joe Biden has made the EU-US rapprochement one of his foreign policy priorities, the policy could be easily reversed by his successor and bring transatlantic relations back to the low points of the Trump years. That volatile period, which still looms over Brussels, put the novel concept of strategic autonomy on the very top of the EU's agenda, a debate once rhetorical that is now bearing its first fruit.
The growing uncertainty around America's electoral cycle is set to be exacerbated by the challenges posed by a pariah Russian state constrained by sanctions but still living side by side with the European Union.
"The next coming years will be years of permanent instability," Lété predicts.
"It will keep bringing Europeans together."