Finland becomes the 31st member of NATO on Tuesday, in a historic strategic shift that began after the war in Ukraine erupted.

Last year, the start of the Ukraine war prompted Finland and its neighbor Sweden to drop decades of military non-alignment.

Turkey and Hungary, for different reasons of their own, delayed Finland's bid to come under the NATO umbrella -- and Stockholm's progress remains blocked.

But last week, the Turkish parliament voted to clear Finland's final hurdle.  

Completing the ratification in well under a year still makes this the fastest membership process in the alliance's recent history.

All that remained were Tuesday's highly choreographed formalities at NATO headquarters.

Finland's Foreign Minister will hand over the formal accession papers to US Secretary of State Antony Blinken, the keeper of NATO's founding treaty.

Then the country's blue-and-white flag will be raised next to those of its new allies, in front of the headquarters in Brussels.

"Not so many years ago we thought it was unthinkable that Finland would become a member. Now they will be a fully-fledged member of our alliance and that is truly historic," NATO Secretary-General Jens Stoltenberg said.

"We are removing the room for miscalculation in Moscow about NATO's readiness to protect Finland, and that makes Finland safer."

Read more: Erdogan gives final ok for Finland's bid to join NATO: Decree

'A big day for Finland'

Finnish Defense Minister Antti Kaikkonen called it "a big day for Finland of course and I'd say it's a win-win situation."

"Our next goal is of course to get our good neighbor Sweden to the full membership as well," Kaikkonen said. 

Joining NATO places Finland under the alliance's Article Five, the collective defense pledge that an attack on one member "shall be considered an attack against them all."

"President Putin had as a declared goal of the invasion of Ukraine to get less NATO," Stoltenberg claimed. 

"He wanted less NATO along his borders. He wanted to close NATO's door. No more NATO membership for any more countries in Europe. He's getting exactly the opposite."

Finland's membership brings into the alliance a military with a wartime strength of 280,000 and one of Europe's largest artillery arsenals.

Read more: Hungary Parliament votes in favor of Finland accession to NATO

Will Sweden join NATO?

The bloc has gone through waves of expansion that brought it ever closer to Russia's borders.

On Monday, Russia said it would boost its military presence in the region in response to Finland joining NATO.

Senior NATO military commander Admiral Rob Bauer told AFP that Finland had so far not requested that its new allies station troops on its soil. 

Budapest and Ankara remain the holdouts after belatedly agreeing to wave through Helsinki's bid without that of Stockholm.

Sweden has upset Hungary's leader Viktor Orban by expressing alarm over the rule of law in Hungary.

Turkey has opposed Sweden's bid, accusing Stockholm of providing a safe haven for what it considers "terrorists", especially members of the Kurdistan Workers' Party (PKK), failing to fulfill the conditions of an agreement signed in Madrid in June.

Ankara also suspended negotiations with Sweden in outrage following rallies attacking the Turkish leadership in Stockholm and the burning of the holy Quran outside Turkey's embassy, but the talks resumed in Brussels on March 9.

One request vs. a long list of conditions
While #Turkey had a long list of conditions from #Finland and #Sweden, all the two Nordic states wanted was to join #NATO.
Here's your guide to understanding on what basis the agreement was made. pic.twitter.com/Aw7Jtu7frp

— Al Mayadeen English (@MayadeenEnglish) June 28, 2022

Read more: Sweden doubts it will join NATO by July: FM

Finland's NATO accession infringes Russia's security: Kremlin

In the same context, Kremlin Spokesperson Dmitry Peskov said on Tuesday that Finland's accession to NATO is another aggravation of the situation, pointing out that Moscow considers the expansion of the alliance an infringement on its security.

"The Kremlin believes that this is another aggravation of the situation. The expansion of NATO is an infringement on our security and Russia's national interests," Peskov told a briefing.

The expansion of NATO forces Russia to take countermeasures to ensure its own security, the Russian diplomat underlined.

"Naturally, this forces us to take countermeasures to ensure our own security both tactically and strategically," he said.

According to Peskov, the situation with Finland's accession to NATO is fundamentally different from the problem with Ukraine, as this country has never had an anti-Russian rhetoric.

"The situation with Finland, of course, is radically different from the situation with Ukraine, because, firstly, Finland has never had anti-Russian rhetoric, and we have had no disputes with Finland. With Ukraine, the situation is the opposite and potentially much more dangerous," the Kremlin Spokesperson explained.

Read more: Ex-Swedish PM: Finland entering NATO first 'not good for Sweden'