TOKYO - Leaders from the Group of Seven industrialized countries on Tuesday warned Russia that any use of a nuclear weapon would be met with "severe consequences," as they reaffirmed their resolve to continue supporting Ukraine in its fight against Moscow's aggression.

The G-7 leaders got together following a wave of Russian attacks in retaliation for an operation attributed to Ukrainian forces late last week that damaged a bridge connecting Russia with Crimea. Moscow responded by unleashing one of its largest missile strikes on Ukraine since its invasion began in late February.

Handout image provided by the German Government Press Office shows German Chancellor Olaf Scholz (2nd from L) taking part in a video conference with other leaders of the Group of Seven and Ukrainian President Volodymyr Zelenskyy on Oct. 11, 2022, in Berlin. (Bundesregierung/Getty/Kyodo)  

"We condemn these attacks in the strongest possible terms," the leaders of Britain, Canada, France, Germany, Italy, Japan and the United States, plus the European Union said in a joint statement, highlighting that civilian infrastructure and cities across Ukraine were targeted.

"Indiscriminate attacks on innocent civilian populations constitute a war crime. We will hold (Russian) President (Vladimir) Putin and those responsible to account," they said.

Fears are also mounting that Russia may use a tactical nuclear weapon for a limited strike in the war against its neighbor, with Japanese Prime Minister Fumio Kishida telling reporters, "We must not make Ukraine a new bombsite of nuclear weapons."

People remove wreckage on a street in Ukraine's capital Kyiv on Oct. 10, 2022, after Russia's missile attacks earlier in the day. (Kyodo) ==Kyodo

After the G-7 virtual meeting, Kishida said the member nations confirmed that Russia's attack on citizens and civilian areas in Ukraine "cannot be justified," while agreeing to strengthen cooperation in tackling Moscow's aggression against Kyiv.

"Threats and use of nuclear weapons by Russia must not happen," Kishida said, adding that the world "must continue the history of no use of nuclear arms."

Ukrainian President Volodymyr Zelenskyy appeared at the outset of the videoconference, saying he cannot hold dialogue with Putin and urging the G-7 countries to reinforce their sanctions against the Russian energy industry.

Zelenskyy, who has been trying to bolster economic and military ties with the G-7 nations, called Putin a "leader without future."

The G-7 leaders deplored in their joint statement what they view as Russia's "escalatory steps," including the partial mobilization of reservists and nuclear saber-rattling.

"We will continue to provide financial, humanitarian, military, diplomatic and legal support and will stand firmly with Ukraine for as long as it takes," they also said, adding that they are committed to supporting Ukraine in meeting its winter preparedness needs.

Russia has said its missile strikes on Monday against Kyiv and other major cities targeted military and energy facilities, while Ukraine said at least 20 people were killed across the country.

Kishida also said Putin's declaration last month of the annexation of four occupied regions amounting to some 15 percent of Ukraine's territory, as well as the supposed referendums in the areas through which Moscow has justified the move, are "unacceptable." Kyiv and the West have condemned the polls as illegitimate.

The G-7 states have been tightening their economic sanctions against Moscow, such as a freeze on assets held by Putin and the country's central bank, and pledging to reduce their reliance on Russian energy resources including natural gas and crude oil.

The virtual summit also came after Japan reopened its embassy in Kyiv last Wednesday following a seven-month closure due to Russia's invasion, in an effort to show the unity of the G-7 states.

The six other G-7 nations already resumed operations at their embassies in Ukraine earlier this year.

Earlier Tuesday, Japanese Foreign Minister Yoshimasa Hayashi said at a press conference that Tokyo has no intention to scale back or stop diplomatic operations in Ukraine's capital again at this juncture.

During the G-7 videoconference, meanwhile, Kishida said he called for the international community to pursue further responses to military threats from North Korea in the wake of a spate of recent ballistic missile launches by Pyongyang.

Photo taken in Ukraine's capital Kyiv on Oct. 10, 2022, shows a building partially destroyed in Russia's missile attacks earlier in the day. (Kyodo) ==Kyodo

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