World leaders are descending on the Japanese city of Hiroshima for this year's Group of Seven (G7) meeting, which is expected to focus on the war in Ukraine and China's rising influence in the Pacific.
US President Joe Biden and Australian Prime Minister Anthony Albanese have arrived in Japan, while several outlets are reporting that Ukraine's leader Volodymyr Zelenskyy will fly in for a surprise visit.
President Zelenskyy has been pressing for more Western support for planes and military equipment as his country prepares to launch a new offensive against Russian forces who first invaded Ukraine last year.
As one of only two cities to experience the utter devastation of nuclear weapons, Japan's Hiroshima makes for a symbolic location to host this year's summit.
Some 80,000 people were killed immediately, a further 60,000 died due to nuclear fallout, and much of the city was reduced to ash and rubble when the United States dropped the world's first nuclear bomb in 1945.
But now, many decades later, experts warn nuclear instability is again on the rise, with Russia hinting at the potential use of nuclear weapons against Ukraine, North Korea's nuclear weapons program, and concern about a conflict between China and the United States over Taiwan.
"We've grown accustomed for decades that nuclear deterrence, nuclear stability was being managed somewhat," said international security expert Corey Wallace from Kanagawa University.
"But over the last decade, over the last few years in particular, the concern about nuclear instability has increased.
"It seems the world is currently at a very, very difficult point."
The G7 countries, representing the wealthiest industrialised nations, have found common ground in condemning Russia's invasion of Ukraine, and labelling its rhetoric over the possible use of nuclear weapons as "irresponsible".
Just last year Mr Biden said the world was the closest it has been to nuclear "armageddon" in over 60 years.
In February, Moscow withdrew from the New START Treaty, which capped the number of strategic nuclear warheads the US and Russia could deploy.
G7 nations also labelled North Korea's nuclear ambitions as a "grave threat to international peace and security", while urging China to abstain from threatening behaviour in the East and South China Seas.
Further sanctions will be applied to Russia, according to Reuters, which Dr Wallace said would also send a strong, unified message to China.
"With [Vladimir] Putin's actions in Ukraine, the concerns about military adventurism in this part of the world have only increased," he said.
"There is a natural connection being made by Japan."
'I worry that Russia may be short-sighted'
For decades, survivors of the Hiroshima bombing, who are known as '"hibakusha", have shared their ordeal of the blast to advocate for a nuclear-free world.
Hiroshi Harada, who was only six at the time of the blast, said he saw blackened corpses and victims with melted skin.
"I worry that Russia may be short-sightedly thinking that it is OK for their country to use nuclear weapons as a matter of course when it comes to the survival of their country," he said.
"It's a big threat.
"These tragic experiences must never happen again."
Japanese Prime Minister Fumio Kishida is from Hiroshima, and has vowed this G7 meeting will send a "strong message" in support of a "world free of nuclear weapons".
He'll be giving a personalised tour of the Hiroshima Peace Memorial, which details the horrors the residents of Hiroshima endured.
"Conveying the reality of the nuclear attack is important as a starting point for all nuclear disarmament efforts," Mr Kishida said.
But his promise to find "concrete steps" on this issue will require delicate diplomacy, as fellow G7 nations the US, France and the UK all possess nuclear weapons.
Japan also enjoys the security of nuclear deterrence due to its alliance with the US.
Simply getting all leaders to attend the Hiroshima Peace Memorial will be chalked up as a symbolic win, but the US has already ruled out an apology to Hiroshima survivors.
The G7 gives emerging powers a seat at the table
This year's G7 meeting has an expanded invite list.
Australia, which shares common security concerns with the G7 nations, is attending.
"A seat at the table means that Australia can have our say," Mr Albanese said after arriving in Hiroshima.
"I look forward to sitting down with our Quad partners as well."
Mr Albanese was forced to scrap a planned summit of Quad leaders from the United States, India, Australia, and Japan in Sydney this week after Mr Biden pulled out.
Fellow Quad member India has refused to openly condemn Russia's invasion of Ukraine, but has endured Chinese aggression over its disputed border.
South Korea is also attending, as it tries to push aside historical grievances with Japan and deepen security cooperation.
The US also recently vowed to send nuclear-armed submarines to South Korea for the first time since the early 1980s, to quell calls in that country to build its own nuclear arsenal to deter Pyongyang.
But the G7 list this year also includes emerging powers Brazil and Indonesia, who have a more neutral stance towards Beijing.
Experts see the expanded list of invitees as a long-term play to counter increasing Chinese influence.
"Tokyo realistically knows it won't push them to an anti-China position," said Robert Dujarric, an expert in Asian studies at Temple University.
"But it's to show them they also have an interest in cooperating with Japan, and to maybe warn them about being more dependent on China. And to basically compete for their attention and their support."
This year's G7 is being held in China's neighbourhood. Beijing is just 1,500 kilometres away from Hiroshima.
And while the meeting takes place, Chinese President Xi Jinping is holding a summit of his own, bringing together Central Asian powers Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan and Uzbekistan.
The meeting, in the historic Silk Road city of Xian, is viewed as Beijing's attempt to shore up support in a region that Russia considers its sphere of influence.
The Pacific to be a key concern at G7
Japan, which is the only non-Western G7 nation, has emphasised prioritising the "Global South", a broad term that encapsulates the entire developing world.
Cook Islands Prime Minister Mark Brown, representing the Pacific Islands Forum, and Comoros President Azali Assoumani, representing the African Union, are also attending the expanded G7.
The Pacific has recently seen a wave of diplomatic activity, after China signed a security pact with Solomon Islands earlier this year.
Africa has experienced a boom in infrastructure funded by Chinese loans, raising concerns many countries are being caught in a so-called "debt trap".
Robert Dujarric said the notion of the "Global South" was flawed, as it encapsulated too many countries with too many varying interests.
He said Japan should focus on its neighbourhood rather than competing with China in Africa.
"They might end up losing money and wasting their resources. There are some countries that do matter and you have to look at it on a case by case basis.
"The resources that Japan invests in national security, defence, foreign aid, and all that, are too limited to allow Japan to play a global role."
