Ukraine crisis: Russia warns of retaliation after Finland moves toward NATO

The Kremlin warned it might take retaliatory "military-technical" steps after Finland's leaders said they favour joining NATO, and Sweden could do the same within days, in a historic realignment triggered by Russia's attack of Ukraine.

Meanwhile, the first war-crimes trial of a Russian soldier since the start of the conflict is set to open Friday in Kyiv. A 21-year-old captured member of a tank unit is accused of shooting to death a civilian in the fighting's first week.

On the ground, Russian forces were pounding areas in central, northern and eastern Ukraine, including the last pocket of resistance in Mariupol, as part of their offensive to take the industrial Donbas region. Ukraine recaptured some towns and villages in the northeast.

Two and a half months after Russia's attack on Ukraine sent a shiver of fear through Moscow's neighbours, Finland's president and prime minister announced Thursday that the Nordic country should apply right away for membership in NATO, the military defence pact founded in part to counter the Soviet Union.

"You (Russia) caused this. Look in the mirror," said Finnish President Sauli Niinisto.

Finland's Parliament still has to weigh in, but the announcement means it is all but certain to apply — and gain admission. The process could take months to complete. Sweden, likewise, is considering putting itself under NATO's protection.

That would represent a major change in Europe's security landscape: Sweden has avoided military alliances for more than 200 years, while Finland adopted neutrality after its defeat by the Soviets in World War II.

Public opinion in both nations shifted dramatically in favour of NATO membership after the attack, which stirred fears in countries along Russia's flank that they could be next.

Such an expansion of the alliance would leave Russia surrounded by NATO countries in the Baltic Sea and the Arctic and would amount to a stinging setback for Russian President Vladimir Putin. He had hoped to divide and roll back NATO in Europe but is instead seeing the opposite happen.

NATO Secretary-General Jens Stoltenberg has said the alliance would welcome Finland and Sweden with open arms.

Russia's Foreign Ministry warned that Moscow "will be forced to take retaliatory steps of military-technical and other characteristics in order to counter the emerging threats to its national security."

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NATO's funnelling of weapons and other military support to Ukraine already has been critical to Kyiv's surprising success in stymieing the attack, and the Kremlin warned anew in chilling terms Thursday that the aid could lead to direct conflict between NATO and Russia.

"There is always a risk of such conflict turning into a full-scale nuclear war, a scenario that will be catastrophic for all," said Dmitry Medvedev, deputy head of Russia's Security Council.

At least two civilians were killed on the outskirts of Kharkiv on Thursday, authorities said. The attacks also damaged a building housing a humanitarian aid unit, municipal offices and hospital facilities, Vyacheslav Zadorenko, the mayor of the suburban town of Derhachi, wrote in a Telegram post.

None of the sites "had anything to do with military infrastructure," Zadorenko said.

Russia's advance in the Donbas has been slow, but its forces have gained some ground and taken some villages.

Britain's Defense Ministry said Russia's focus on the Donbas has at the same time left its remaining troops around Kharkiv vulnerable to counterattack from Ukrainian forces, which recaptured several nearby towns and villages.

In other developments, Ukrainian officials said their forces took out another Russian ship in the Black Sea.

The Vsevolod Bobrov logistics ship was badly damaged but not thought to have sunk when it was struck while trying to deliver an anti-aircraft system to Snake Island, said Oleksiy Arestovych, an adviser to the Ukrainian president.

A spokesman for the Odesa regional military administration said the vessel caught fire after the strike. There was no confirmation from Russia and no reports of casualties.

Twelve Russian missiles struck an oil refinery and other infrastructure in the central Ukrainian industrial hub of Kremenchuk on Thursday, the region's acting governor, Dmytro Lunin, wrote in a Telegram post. In early April, he said, the refinery, which had been the last fully functional one in Ukraine at the time, was knocked offline by an attack.

The southern port of Mariupol has largely been reduced to smoking rubble with little food, water or medicine, or what the mayor called a "medieval ghetto." Ukrainian fighters there continued to hold out at the Azovstal steel plant, the last stronghold of resistance in the city.

Ukrainian Deputy Prime Minister Iryna Vereshchuk said negotiations were underway with Russia to win the release of 38 severely wounded Ukrainian defenders from the plant. She said Ukraine hoped to exchange them for 38 "significant" Russian prisoners of war.

• Europe