Ukraine is expected to dominate talks at the G7 summit.

HIROSHIMA, Japan — President Biden embarked on a shortened Asia trip Thursday in Hiroshima, a city symbolic of the horrors of armed conflict, for a summit with its allies expected to be dominated by discussions on how to better Ukraine now armed its counter-offensive against the Russian invaders.

The meeting of the leaders of the Group of 7 countries starting Friday comes at a critical time for President Volodymyr Zelensky of Ukraine, his country and the Western core democracies now preoccupied with an urgent mission to bring about what Mr. Biden calls the “strategic defeat.” of Russia in Ukraine.”

Mr. Biden often says that Russia is already defeated. But the fear that pervades the seven major democracies here is that unless the counter-offensive proves very successful, Ukraine will plunge into a bloody, frozen conflict in which the best hope would be a ceasefire, reminiscent of the conflict that a ended the fighting on the Korean Peninsula 70 years ago this summer.

That seemed almost impossible to imagine in 1997, when President Bill Clinton and Prime Minister Tony Blair of Britain invited Russia to become a full member of the group and expand it — for nearly two decades — to the G8. Russia was “suspended” after annexing Crimea in 2014 and withdrew from the group three years later.

With his troops already trying to destroy Russian arms depots ahead of the counter-offensive, Mr. Zelensky has just completed a series of rapid-fire visits to European capitals to rally support for continued heavy spending on armaments and aid. He is expected to address leaders in Hiroshima virtually, but there have been talks behind the scenes about the risk of bringing him in person to the other side of the world to make his case.

Anyway, he will have a large audience. In addition to India, the leaders of Australia, South Korea, Brazil, Indonesia and Vietnam will also be present as guests. It is part of a broader strategy by Mr Biden and his allies to attract nations that are, to varying degrees, witchers of war, who refuse to condemn Russia too harshly, enthusiastically enforce sanctions or supply weapons to Ukraine.