Hiroshima. Leaders of the world’s most powerful democracies huddled Friday to discuss new ways to punish Russia for its 15-month invasion of Ukraine, days before President Volodymyr Zelensky joins the Group of Seven summit in person on Sunday.

Zelensky will be making his furthest trip from of his war-torn country as leaders are set to unveil new sanctions on Russia for its invasion. Oleksiy Danilov, the secretary of Ukraine’s National Security and Defense Council, confirmed on national television that Zelensky would attend the summit.

“We were sure that our president would be where Ukraine needed him, in any part of the world, to solve the issue of stability of our country,” Danilov said Friday. “There will be very important matters decided there, so physical presence is a crucial thing to defend our interests”.

Russian President Vladimir Putin’s nuclear threats against Ukraine, along with North Korea’s months-long barrage of missile tests and China’s rapidly expanding nuclear arsenal, have resonated with Japan’s push to make nuclear disarmament a major part of the summit. World leaders Friday visited a peace park dedicated to the tens of thousands who died in the world’s first wartime atomic bomb detonation.

Japanese leader Fumio Kishida said he invited Zelensky to the G7 Summit during his visit to Kyiv in March.

Zelensky is also set to appear virtually at a Friday meeting of G7 leaders, where they are to be updated on battlefield conditions and agree to toughen their efforts to constrain Moscow’s war effort.

After group photos near the city's iconic bombed-out dome, a wreath-laying and a symbolic tree planting, a new round of sanctions were to be unveiled against Moscow, with a focus on redoubling efforts to enforce existing sanctions meant to stifle Russia's war effort and hold accountable those behind it, a U.S. official said. Russia is now the most-sanctioned country in the world, but there are questions about the effectiveness of the financial penalties.

The U.S. official, speaking on the condition of anonymity to preview the announcement, said the U.S. component of the actions would blacklist about 70 Russian and third-country entities involved in Russia's defense production, and sanction more than 300 individuals, entities, aircraft and vessels.

The official added that the other G7 nations would undertake similar steps to further isolate Russia and to undermine its ability to wage war in Ukraine. Details were to emerge over the course of the weekend summit.

The European Union was focused on closing the door on loopholes and plans to restrict trade in Russian diamonds, Charles Michel, president of the European Council, told reporters early Friday.

He said the G7 would also try to convey to leaders of countries that are non-member guests at the summit why it's so important to enforce sanctions.

Japanese Prime Minister Fumio Kishida, who represents Hiroshima in parliament, wants nuclear disarmament to be a major focus of discussions, and he formally started the summit at Hiroshima's Peace Memorial Park. The visit by world leaders to a park dedicated to preserving reminders of Aug. 6, 1945, when a U.S. B-29 dropped an atomic bomb over Hiroshima, provided a striking backdrop to the start of the summit. An estimated 140,000 people were killed in the attack, and a fast-dwindling number of now-elderly survivors have ensured that Hiroshima has become synonymous with anti-nuclear peace efforts.

“Honestly, I have big doubts if Mr. Kishida, who is pursuing a military buildup and seeking to revise the pacifist constitution, can really discuss nuclear disarmament,” Sueichi Kido, a 83-year-old “hibakusha” or survivor of the Nagasaki explosion, told The Associated Press. “But because they are meeting in Hiroshima I do have a sliver of hope that they will have positive talks and make a tiny step toward nuclear disarmament.”

As G7 attendees made their way to Hiroshima, Moscow unleashed yet another aerial attack on the Ukrainian capital. Loud explosions thundered through Kyiv during the early hours, marking the ninth time this month that Russian air raids have targeted the city after weeks of relative quiet.

“The crisis in Ukraine: I’m sure that’s what the conversation is going to start with,” said Matthew P. Goodman, senior vice president for economics at the Center for Strategic and International Studies.

Speaking to reporters aboard Air Force One, Jake Sullivan, the White House national security adviser, said there will be “discussions about the battlefield” in Ukraine and on the "state of play on sanctions and the steps that the G7 will collectively commit to on enforcement in particular.”

The United States has frozen Russian Central Bank funds, restricted banks’ access to SWIFT -- the dominant system for global financial transactions -- and sanctioned thousands of Russian firms, government officials, oligarchs and their families.

The Group of Seven nations collectively imposed a $60 per-barrel price cap on Russian oil and diesel last year, which the U.S. Treasury Department on Thursday defended in a new progress report, stating that the cap has been successful in suppressing Russian oil revenues. Treasury cites Russian Ministry of Finance data showing that the Kremlin’s oil revenues from January to March this year were more than 40% lower than last year.