The United States has been attempting to bridge the gap between Ukraine and Russia in the last two months, in a bid to bring about an end to the three-year-old war.
But so far, a breakthrough has seemed elusive between the two sides, who remain at odds on a number of points.
So what do Vladimir Putin and Volodymyr Zelenskyy want to see done?
'Unconditional ceasefire'
Both Ukraine and Russia have wanted to see a ceasefire put in place before a formal agreement to end the war.
Zelenskyy has suggested a "total and unconditional ceasefire" would need to be in place before he is willing to sit down at the negotiating table with Russia.
But Putin appears unwilling to agree, instead setting a string of conditions for what needs to happen before a negotiated end to the war.
He has argued a truce would help Kyiv's military, while Ukraine and its European allies have accused Putin of not wanting peace.
Russia has declared a three-day ceasefire next week to coincide with commemorations of the end of World War II in Europe.
It follows a similar ceasefire declared by Putin over Easter, which Ukrainian leaders later said was breached repeatedly by Russian forces.
Western aid and NATO
Ukraine has long sought to move closer to Europe and the United States militarily, even pushing to join the North Atlantic Treaty Organisation (NATO).
Such a step has been resisted by both Russia, and, more recently, by the Trump administration.
Putin has long argued NATO expansion has encroached on Russia's sphere of influence, even citing that as a reason for invading Ukraine.
A key demand of Russia is that Ukraine be barred from joining NATO after the war. The Kremlin also wants an end to Western arms deliveries to Ukraine and no Western peacekeeping troops in Ukraine post-war.
But Zelenskyy has called for increased Western support after the war, including a Western military contingent in the country to secure any ceasefire.
Several European allies, including the UK and France, have said they are ready to send peacekeeping troops.
Territorial concessions
Russia, which controls around one-fifth of Ukraine's territory, has made repeated demands for Kyiv to officially cede its claim those territories.
Moscow in 2022 unilaterally declared it had annexed four Ukrainian regions — the Donetsk, Lugansk, Zaporizhzhia and Kherson — despite not having full control over them.
Since 2014, Russia has also had control of Crimea, after annexing it from Ukraine in a move deemed illegal and not recognised internationally.
Russian Foreign Minister Sergei Lavrov has said that recognition of Moscow's ownership of these territories is "imperative" for any negotiations.
Kyiv has said it will not recognise its occupied territories, including Crimea, as Russian.
Until recently, Ukrainian forces had also occupied a small piece of Russia's Kursk region, territory which Kyiv hoped would become a bargaining chip in negotiations with Russia.
The Kremlin has since claimed it has pushed Ukraine's military out of Kursk, a claim disputed by Kyiv.
US minerals deal
The US and Ukraine have been attempting to negotiate a deal which would see both countries mine rare earth minerals in Ukraine.
Such an agreement would involve opening American access to Ukraine's resources, in exchange for security guarantees.
While the US sees this as a route to recouping the billions of dollars America has sent Ukraine in aid, Washington also believes Putin would be less likely to launch a further attack if US interests were invested in Ukraine.
Earlier this week, a Ukrainian foreign ministry spokesperson said Kyiv wanted to finalise a "mutually beneficial deal" with the US as soon as possible.
It would likely be opposed by Putin and it is unclear if it could complicate peace negotiations.
What are the chances of success?
The increasing willingness of both sides to at least consider temporary ceasefires has boosted optimism about a breakthrough between the two sides.
But King's College Professor Lawrence Freedman said he would "be surprised" if Putin agreed to an indefinite ceasefire to allow negotiations to take place, as Zelenskyy had called for.
"We may have a succession of short ceasefires to give a chance for negotiations or something like that," he said.
But Professor Freedman also said that while "the positions of the two sides are so incompatible", both leaders had their reasons for wanting a deal.
He pointed to Russia's economy, which has been under strain due to wartime spending and falling oil prices, as a potential reason why Putin may want to make some concessions.
"People regularly talk as if Russia is making great advances by the day, but it isn't. It's achieved very little, actually, since late [2023]."
ABC/Reuters/AFP
