BRUSSELS • 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 — and possible political trouble in Turkey.

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 Secretary-General Jens Stoltenberg, head of the alliance.

The 30 ambassadors and permanent representatives formally approved decisions made at a NATO summit in Madrid last week, when the leaders of member nations invited Russia’s neighbor Finland and Scandinavian partner Sweden to join the military club.

Securing parliamentary approval for the new members in Turkey, however, could still pose a problem even though Sweden, Finland and Turkey reached a memorandum of understanding at the Madrid summit.

Turkish President Recep Tayyip Erdogan warned that Ankara could block the process if the two countries failed to grant Turkey’s demands for the extradition of people it views as terror suspects. The people wanted in Turkey have links to outlawed Kurdish groups or the network of an exiled cleric accused of a failed 2016 coup in Turkey.

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.

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,” he said.

Finland’s Foreign Minister Pekka Haavisto, left, Sweden’s Foreign Minister Ann Linde, right, and NATO Secretary General Jens Stoltenberg meet Tuesday after the signature of the NATO Accession Protocols for Finland and Sweden in the NATO headquarters in Brussels.

the associated press