- With Finland and Sweden both announcing their bids to join the Western military alliance NATO on Sunday, ending a long modern history of military nonalignment, all eyes are on Russia's reaction.
- Moscow has already expressed outrage at the idea of its old foe NATO's potential imminent expansion, warning it would take "retaliatory steps" against the organization.
- Geopolitical experts are assessing the possible actions Russia could take.
With Finland and Sweden both announcing their bids to join the Western military alliance NATO, ending a decades-long history of military nonalignment, all eyes are on Russia and how it might react.
Moscow has already expressed outrage at the idea of its old foe NATO's potential imminent expansion soon after Finland announced its intention to apply to the organization last week.
Now that Finland has officially confirmed that it will apply — with Sweden's governing Social Democratic Party similarly backing a bid to join NATO — Moscow has wasted no time in making its feelings known, with Russian President Vladimir Putin saying Monday that the expansion of NATO "is a problem."
Putin claimed that the move was in the interest of the U.S., in comments reported by Reuters, and said Russia would react to the expansion of military infrastructure to Sweden and Finland, although he insisted Moscow had "no problems" with the countries.
Putin's comments come after other top Kremlin officials deplored the future expansion of NATO, with one describing it is a "grave mistake" with global consequences.
Finland's and Sweden's membership in NATO is not a done deal yet as any decision on enlargement requires the approval of all 30 members of the alliance and their parliaments — and Turkey has already voiced objections.
With these obstacles expected to be overcome, however, geopolitical experts are looking ahead and assessing the possible "retaliatory steps" Putin — who has made no secret of his loathing for NATO — could take.
Over the years, Russia has made repeated provocative incursions near or into NATO allies' airspace and these seem to have increased in frequency in the last few years. With Sweden's and Finland's latest move to join NATO, experts believe the alliance should prepare itself for more provocations from Russia.
"This changes the security environment for the entire Baltic Sea and for the Arctic," retired Lt. Gen. Ben Hodges, former commanding general of the U.S. Army in Europe, told CNBC on Monday.
"Of course there will continue to be airspace violations, just like there are over other NATO countries, but we're a defensive alliance and we're going to react coolly and professionally. The last thing that the Russians want is to get into a fight with all 30 NATO nations, soon to be 32," he told CNBC's "Capital Connection."
"[Putin's] going to complain about it, he's going to threaten things but he actually has nothing that he can do as most of his military is tied up in Ukraine, so I don't see any real threat against Sweden or Finland."
Russian provocations of NATO are nothing new. In 2020, NATO air forces across Europe were scrambled more than 400 times to intercept unknown aircraft approaching the alliance's airspace with almost 90% of these missions in response to flights by Russian military aircraft, NATO said in a statement.
Last March, NATO planes were scrambled 10 times in a six-hour period in response to an "unusual peak" of Russian warplanes near the alliance's airspace over the North Atlantic, North Sea, Black Sea and Baltic Sea.
NATO has said Russian military aircraft often do not transmit a transponder code indicating their position and altitude, do not file a flight plan, or do not communicate with air traffic controllers, posing a potential risk to civilian airliners.
Sweden and Finland have both insisted that joining NATO is not a move against Russia but both concede the decisions have been taken in light of Moscow's unprovoked invasion of Ukraine.
Sweden's prime minister, Magdalena Andersson, told CNBC on Sunday that her country felt NATO membership was the best thing for its security, saying "what kind of retaliation there can be is up to Putin, we see there can be cyberattacks and hybrid attacks and other measures, but it is all up to them," she told CNBC's Steve Sedgwick in Stockholm.
Meanwhile, Swedish Foreign Minister Ann Linde said in the transition period before Sweden and Finland become full NATO members, heightened tensions are likely, noting "we foresee more military troops close to our border."
Another potential space for retaliation, and possible Russian punishment for NATO's expansion, could come in the energy sphere.
Russia still holds a powerful card in this area because it has traditionally accounted for around 40% of the EU's gas imports. And while Europe scrambles for alternative energy sources to reduce its dependence on Russia as a provider of oil and gas, it is still reliant on it.
Gilles Moec, group chief economist at AXA Investment Managers, said in a note Monday that there was an "ever so present possibility Russia 'turns the tap off' its supply to the EU" although he noted that, so far Moscow has restricted itself to "half measures" which have not dried up supply — reflecting the country's own dependence on these financial resources.
A day after Finland's leaders announced their support for NATO membership, Russian state-owned utility company Inter RAO announced it would stop exporting electricity to Finland from Saturday (Finland gets about 10% of its electricity from Russia) citing a lack of payment as a reason, although the move was widely seen as retaliatory.
On Monday, Russia's deputy foreign minister, Sergei Ryabkov, issued a statement in which he said Sweden's and Finland's bids to join NATO were "another grave mistake with far-reaching consequences," Russia's Interfax news agency reported.
Ryabkov added that Finland and Sweden should have no illusions that Russia will simply put up with their decision.
"The security of Sweden, like Finland, for that matter, will not be strengthened as a result of this decision, it is quite obvious to us," he told reporters in Moscow.
"And in what form we will ensure our security after the change in this general NATO configuration is a separate question. It will depend on what, in practical terms, will be the result of the expected accession of Finland and Sweden to the alliance. There are no illusions that we will put up with it," Ryabkov stressed.
Russia has long been very wary about NATO's existence, let alone its expansion, which it has long opposed. Moscow's antipathy is not surprising given the alliance was founded in 1949 by the U.S., Canada
and several Western European nations to provide collective security against the then-Soviet Union.
Over much of the 20th century, animosity between the West and Russia was concentrated in the long-running Cold War but even after the Soviet Union collapsed in 1991, tensions between Russia and NATO have continued, despite brief spells of more cordial relations.
In recent years, as relations between Russia and the West have deteriorated, Putin has repeatedly voiced his criticism of NATO and has framed Russia's national identity and geopolitical status in opposition to the alliance. Russia has justified its invasion of Ukraine in large part on the false premise that NATO is fighting a proxy war against it, in Ukraine.
Ahead of the invasion on Feb.24, Moscow had issued a list of demands to the West, including that Ukraine would never be allowed to join NATO. The West refused.