The 30 NATO allies signed off on the accession protocols for Sweden and Finland on Tuesday, sending the membership bids of the two nations to the alliance capitals for legislative approvals.

The move further increases Russia's strategic isolation in the wake of its invasion of neighboring Ukraine in February and military struggles there since.

"This is truly a historic moment for Finland, for Sweden and for NATO," said alliance Secretary-General Jens Stoltenberg.

The 30 ambassadors and permanent representatives formally approved the decisions of last week’s NATO summit when the alliance made the historic decision to invite Russia’s neighbor Finland and Scandinavian partner Sweden to join the military club.

Parliamentary approval in member state Turkey could still pose problems for their final inclusion as members, despite a memorandum of understanding reached between the three.

Last week, President Recep Tayyip Erdoğan warned that Ankara could still block the process if the two countries fail to fully meet Turkey’s demand to extradite terror suspects with links to terrorist groups.

He said Turkey’s Parliament could refuse to ratify the deal. It is a potent threat since NATO accession must be formally approved by all 30 member states, which gives each a blocking right.

Foreign Minister Mevlüt Çavuşoğlu on Monday echoed similar views and said Sweden and Finland have to comply with the recent memorandum signed with Turkey to be part of NATO.

"If they do not comply, we will not accept them into NATO," he underlined.

Stoltenberg said he expected no change of heart. "There were security concerns that needed to be addressed. And we did what we always do at NATO. We found common ground."

At a news conference, the foreign ministers of Sweden and Finland were peppered with questions about whether a specific list of people would need to be extradited to Turkey, but both said such a list was not part of the memorandum with Ankara.

"We will honor that memorandum and follow up on that," said Swedish Foreign Minister Ann Linde, adding her government's actions would always "comply with the Swedish legislation. We will comply with international law."

She added, though, that "we will see to it that we have a mechanism of fighting terrorism in all its forms."

Every alliance nation has different legislative challenges and procedures to deal with, and it could take several more months for the two to become official members.

"I look forward to a swift ratification process," said Finnish Foreign Minister Pekka Haavisto. The Russian invasion of Ukraine has given the process added urgency. It will ensconce the two nations in the Western military alliance and give NATO more clout, especially in the face of Moscow’s military threat.

"We will be even stronger and our people will be even safer as we face the biggest security crisis in decades," said Stoltenberg.

Tuesday’s signing-off does bring both nations deeper into NATO’s fold already. As close partners, they already attended some meetings that involved issues that immediately affected them. As official invitees, they can attend all meetings of the ambassadors even if they do not yet have any voting rights.

Nordic countries' membership applications were held up until the last moment by Turkey, which sought guarantees that the Nordic countries would join Turkey’s fight against PKK-linked terrorists and swiftly extradite suspects. The dispute was resolved by a 10-point memorandum, signed last Tuesday, that appeared to address many of Turkey’s terrorism concerns and lift an arms embargo on Ankara imposed in response to Turkey’s 2019 military operation into Syria.

New countries’ membership applications must be approved by all NATO member states and ratified by the countries’ respective parliaments.

The deal also states that Finland and Sweden will work closely with Turkey on issues related to the exchange of information, extradition and, in general, the fight against terrorism.

After four hours of talks in Madrid last Tuesday, Erdoğan and his Finnish and Swedish counterparts agreed on a series of security measures to allow the two Nordic countries to overcome the Turkish veto.

The memorandum was signed by the foreign ministers of the three countries, Turkey's Çavuşoğlu, Pekka Haavisto of Finland and Ann Linde of Sweden, in the presence of all three leaders and Stoltenberg.

According to the signed memorandum, Finland and Sweden pledged not to support the PKK/YPG or the Gülenist Terror Group (FETÖ), which orchestrated a 2016 coup attempt and is led by U.S.-based Fetullah Gülen. The signed memorandum did not list any individuals for extradition. Ratification in allied parliaments is likely to take up to a year, but once it is done, Finland and Sweden will be covered by NATO’s Article 5 collective defense clause, putting them under the United States’ protective nuclear umbrella.

Meanwhile, a Swedish independent politician who is a supporter of the YPG/PKK terrorist organization filed a criminal complaint Monday against Foreign Minister Linde.

Sweden's official news agency TT reported that Amineh Kakabaveh filed the criminal charges against Linde with the Constitutional Commission on the grounds of her attitude towards the tripartite memorandum signed between Turkey, Finland and Sweden on the Nordic countries' bids for NATO membership

The report said Kakabaveh was upset over Sweden's promise to export arms to Turkey and she also wanted an article of the memorandum stating that Sweden would extradite criminals to Ankara to be examined.