Russia's invasion of Ukraine has led to warnings from Moscow and Washington that one false move could precipitate a catastrophic global conflict.
But while the threat of World War Three remains a clear and present danger, it is perhaps little known that Russia remains locked in a territorial dispute with Japan that hasn't been resolved since World War Two and has meant the two sides have never signed a peace treaty.
And on Monday, 77 years after peace talks started between the two major powers, they broke down once again over Russia's continued invasion of Ukraine.
At the heart of the dispute is a disputed set of islands known in Russia as the Kuril Islands and in Japan as the Northern Territories.
Yahoo News UK outlines why a disputed set of islands means the two nations technically remain at war, and why talks have rumbled on for so long.
On Monday evening, Russia officially withdrew from peace treaty talks following Tokyo's imposition of sanctions in response to Putin's invasion of Ukraine.
In a statement, the Russian Foreign Ministry said: "Under the current conditions Russia does not intend to continue negotiations with Japan on a peace treaty."
It accused Japan of adopting "openly unfriendly positions and attempts to damage the interests of our country".
In response, Japan's prime minister, Fumio Kishida, criticised Russia's withdrawal. "This entire situation has been created by Russia's invasion of Ukraine, and Russia's response to push this on to Japan-Russia relations is extremely unfair and completely unacceptable."
What sanctions has Japan taken?
Japan has imposed sanctions on 76 individuals, seven banks and 12 other bodies in Russia, including defence officials and its state-owned arms exporter, Rosoboronexport.
Last week, Japan said it plans to revoke Russia's most-favoured-nation trade status and ban imports of certain products.
Kishida has made clear Tokyo will remain aligned with the US and its Nato allies, saying: "Japan must resolutely continue to sanction Russia in co-operation with the rest of the world."
Are Russia and Japan really still at war?
In the aftermath of the Second World War, which finished in 1945, the nations involved in the conflict tried to come together to agree on various peace settlements after the complete surrender of Japan.
The Treaty of San Francisco, also called the Treaty of Peace with Japan, was signed by 49 countries in 1951, but the Soviet Union was not one of them.
Five years later, the two countries came together to sign the Soviet-Japanese Joint Declaration of 1956, which ended the state of war between them and restored diplomatic relations.
The declaration also included an agreement to sign a future peace treaty, but that has not yet been achieved.
This is why talks were still going on almost 80 years after World War II ended, before Russia's withdrawal this week.
So while the 1956 declaration ended fighting between Russia and Japan, the hostilities won't technically be over until a peace treaty is signed.
What is the dispute?
Each nation claims ownership over the islands in waters between the two countries.
This archipelago sits just off Japan's northernmost island of Hokkaido.
Japan took the islands during the Russo-Japanese War in 1904-1905, but they were seized by the Soviet Union at the end of World War II.
Watch: Kyiv mayor Vitali Klitschko attacks Putin: 'He's sick, he's an unhealthy man'
They stretch 1,300km (810 miles) and are made up of 56 islands and have been administered by Russia ever since.
Japan claims the southernmost islands of the archipelago, which includes most of the largest and only habitable territory.
In 2016, Putin offered some hope that a resolution could be found, telling Japanese journalists that while there remained a "chance" it was difficult to say how big that was “because it depends on factors including the flexibility of our partners”.
The Russiam President has always been cautious of giving too much away, saying: “We think that we have no territorial problems. It’s Japan that thinks that it has a territorial problem with Russia,” he said in 2016.
By 2020, little had been resolved and Russia's constitution was then amended to bar handing over territory to a foreign power.
However, last year, President Putin said that both Tokyo and Moscow wanted good relations and that it was absurd they had not reached a peace agreement.
According to Professor Yoko Hirose at Keio University, the normalisation of relations between the two powers could lead to future economic co-operation that could have a stabilising effect on the region.
It may also act as a buffer to prevent closer co-operation between China and Russia.
However, while Putin continues with his campaign in Ukraine, then it seems unlikely there will be any resolution in the near future.
Watch: Russians protest against potential Kuril Islands handover to Japan