Russia halted electricity deliveries to Finland on Saturday after President Putin warned that abandoning military neutrality to join NATO would be wrong.
Putin told Niinisto that applying to join NATO could have a negative effect on Russian-Finnish relations.
According to Niinisto's office, he said on the call that Russian demands last year to prevent countries from joining NATO and the invasion of Ukraine have changed the security environment of the country.
Niinisto told Putin that he will apply for NATO membership.
Russian power grid operator Inter RAO cut off electricity exports to Finland on Saturday due to sanctions, and Putin and Niinisto called on the government to find a solution.
Russian electricity accounts for 10% of Finns consumption, but it does not expect electricity shortages, according to the grid operator.
Reima Päivinen said in a statement that Finns will replace electricity with domestic production or imports from Sweden.
Jukka Leskel, managing director of the Finnish Energy industry association, told YLE that the timing of the electricity cut off was questionable and that he believed it was related to the NATO decision.
Following Russia's invasion of Ukraine, Sweden and Finland have been conducting security reviews. The security landscape has completely changed after the day Russia invaded, according to Swedish Prime Minister Magdalena Andersson. Russia warned that it would have to balance the situation with military and political consequences if it joined NATO. Russia invaded Finland in 1939 and caused a year-long war in which it ceded a quarter of its territory to Russia.
While NATO Secretary-General Jens Stoltenberg has repeatedly said he expects all allies to welcome Sweden and Finland if they apply for membership, Turkish President Recep Tayyip Erdogan said Turkey doesn't want the two countries joining NATO on Friday. Ibrahim Kalin, a spokesman for the president, said on Saturday that Turkey isn't trying to block the bids of Sweden and Finland, but wants to make sure that the national security of all NATO members is taken into account. All 30 members of the alliance have to approve new countries.
Sweden is expected to make a decision on whether to join the alliance on Sunday. On Thursday, Niinisto and Sanna Marin announced their support for the move, and last month the foreign minister indicated that Sweden could apply for NATO membership within days.
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