In a strategic blow to Russia’s strongman leader, Finland will join NATO Tuesday. Sweden, which has also aimed to become a member, will be left behind, exposing fissures inside the alliance. 

The announcement that Finland would join NATO without its Nordic partner has increased anger at Turkey among members of the North Atlantic Treaty Organization. President Erdogan and Hungary’s prime minister, Viktor Orbán, held up the expansion for months, with each looking for concessions from the European Union and, even more so, from Washington. 

On Tuesday, “we will raise the Finnish flag for the first time here at the NATO headquarters,” the alliance’s secretary-general, Jens Stoltenberg, said Monday. “It will be a good day for Finland’s security, for Nordic security, and for NATO as a whole.”

Finland’s shared border with Russia is more than 800 miles long, which is creating new headaches for President Putin, who had justified his invasion of Ukraine by claiming it was a response to NATO’s expansion. 

Mr. Putin is considered a “strategic genius” by some, a military watcher and senior director at the Foundation for Defense of Democracies, Bradley Bowman, says. Yet, Finland — which, as he notes, possesses more artillery power than Britain, France, and Germany combined — is now a member of the alliance and formally becomes part of its war plans.

“Once a country joins NATO Putin can’t invade it, and that creates an additional dilemma when Russia plans new aggression,” Mr. Bowman tells the Sun. 

For decades prior to Russia’s invasion, Sweden and Finland maintained neutrality between Russia and the West. Spooked by last February’s invasion, though, the two vowed to join NATO — and to do so in tandem. 

Finland’s now-outgoing prime minister, Sanna Marin, hosted her Swedish counterpart, Ulf Kristersson, at Helsinki in October. “It is very important for us, of course, that Finland and Sweden would join NATO hand in hand,” she said. Yet, as Ankara increasingly made clear that it mostly objects to Sweden, Finland joined without its partner. 

“Sweden is not left alone,” Mr. Stoltenberg said Monday. “Sweden is as close as it can come as a full-fledged member.” He may have omitted the but no cigar part of the statement. 

“We encourage Türkiye to quickly ratify Sweden’s accession protocols as well,” the American national security adviser, Jacob Sullivan, said last month. Yet, whatever pressure Washington mounted on Mr. Erdogan, he is yet to remove his Sweden veto, which has always been stronger than his objection to Finland  

“For a while, Turkey treated Finland and Sweden as a package deal, but it was more about Sweden than Finland,” a former NATO adviser who is now running the Black Sea Program at the Middle East Institute, Julia-Sabrina Joja, tells the Sun. 

Sweden, which currently holds the European Union’s presidency, has sharply criticized Turkey’s record on human rights and the rule of law. Sweden is also home for exiled Turkish-Kurds, including members of the PKK, which Turkey considers a terrorist organization. 

Hungary, meanwhile, hopes to shore up its economy by receiving EU loans and aims to pressure Brussels by holding up support for Sweden’s NATO accession. Yet, Europeans widely assume that if Turkey reverses its objection to Stockholm, Hungary will quickly follow suit.  

Above all, Mr. Erdogan is using his NATO veto power as a negotiation tool with Washington. President Biden achieved very little in foreign policy beside building a strong alliance for the war on Ukraine, Ms. Joja says. At the same time, she adds, Turkey has used its “strategic ambiguity” to increase leverage in talks with America.

Turkey declined to join Mr. Biden’s sanctions against the Kremlin elites, trading goods with Moscow instead. Ankara attempted to play peacemaker, maintaining ties with both sides of the Ukraine war. Its stance on the war frustrated Washington and added to past grievances — most notably Turkey’s purchase of Russian S-400 systems instead of American-made anti-aircraft batteries that are standard in NATO. 

“Turkey is a NATO ally that often doesn’t act like one,” Mr. Bowman says. Ankara has “built a crazy amount of dependence on America’s adversaries, China and Russia,” Ms. Joja adds. 

As next month’s Turkish presidential election nears, Mr. Erdogan hopes to use the NATO expansion issue to bolster his image at home as a strong independent player who is able to push around America. At the same time, Sweden’s hopes of joining NATO may not be at a dead end.

“Turkey is an important NATO ally, but it’s a mixed bag,” a senior fellow and Europe watcher at the American Enterprise Institute, Dalibor Rohac, tells the Sun. Ankara, he adds, seeks concessions from the U.S., hoping to receive arms in return for removing its objections to NATO expansion. “So there is a path,” he says, adding however, “I’m not sure that it’s great for the alliance that a member tries to get concessions for itself” in return for expanding NATO. 

While Finland’s accession may strengthen NATO’s stance against Moscow, Turkey’s fight against Sweden exposes some of its weaknesses.