Russia will have to bolster its defenses in the Baltic Sea -- including a potential nuclear escalation -- if Sweden and Finland join NATO, Moscow said on Thursday.

"There can be no more talk of any nuclear-free status for the Baltic - the balance must be restored," Dmitry Medvedev, deputy chairman of Russia’s security council and former president of Russia, said, Reuters reported.

"Until today, Russia has not taken such measures and was not going to. If our hand is forced, well ... take note it was not us who proposed this," he added, according to Reuters.

Medvedev's warning came as Sweden and Finland seem closer than ever before to joining the Western alliance.

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Finland and Sweden’s prime ministers held a joint news conference in Stockholm on Wednesday, with Finnish Prime Minister Sanna Marin saying the country would decide within the next few weeks on NATO membership and Swedish Prime Minister Magdalena Andersson saying her country is making the same calculation. Finland shares a significant land border with Russia.

Deputy chairman of the Russian Security Council Dmitry Medvedev speaks during a meeting with members of the Security Council in Moscow on February 21, 2022. (Photo by ALEXEY NIKOLSKY/Sputnik/AFP via Getty Images)

Lithuanian Defense Minister Arvydas Anusauskas said Russia already has nuclear weapons in the area, according to Sky News.

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"The current Russian threats look quite strange when we know that, even without the present security situation, they keep the weapon 100 km from Lithuania's border," Anusauskas said. "Nuclear weapons have always been kept in Kaliningrad. The international community, the countries in the region, are perfectly aware of this. They use it as a threat."

Lithuanian Prime Minister Ingrida Simonyte also dismissed the threat.

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"That Russia threatens, it is nothing new," Simonyte said Thursday, according to the Independent. "Kaliningrad is a very militarized zone, has been for many years, and it is in the Baltic region."