Experts have warned the deteriorating relationship between Ukraine and the United States could have "seismic" consequences for diplomacy, US foreign policy, and international security.
It comes after a heated public exchange between Ukrainian President Volodymyr Zelenskyy, US President Donald Trump and US vice president JD Vance, which led to the cancellation of the signing of
The meeting culminated in a dressing-down of the Ukrainian leader, with Trump saying Zelenskyy was in a "very bad position" and "gambling with World War Three".
Associate Professor Matthew Sussex, from the Centre for European Studies at the Australian National University, described the incident as "extraordinary".
"It's totally unprecedented," he said.
"It is the most extraordinary display of attempts at public humiliation I think that we've ever seen out of American diplomacy."
What is Ukraine's history with the US?
The US formally established diplomatic relations with Ukraine in 1991 after its independence from the Soviet Union.
In 1994 under then-US president Bill Clinton, the Budapest Memorandum was signed by the US and Russia, along with the UK and Ukraine.
Under the agreement, Ukraine agreed to give up its nuclear weapons in exchange for other parties respecting its sovereignty and providing security assurances.
In 2014, when Russia annexed Crimea, the US responded with sanctions against Russia and provided aid to Ukraine.
The relationship between Ukraine and the US has been deteriorating. Source: AAP / Pool/ABACA/PA
But under the Trump administration, the relationship appears to be declining — the recent outburst being just the most public display of the administration's shifting support for Ukraine.
"This is a pretty major reversal, in terms of the history of America supporting Ukraine," Sussex said.
"And I think the most galling thing is that the US, through coercing Ukraine like this, is now in violation of the very document it negotiated in 1994 that was supposed to keep the Ukrainians safe."
The personal relationship between Trump and Zelenskyy, as well as the Trump administration's approach to foreign policy and diplomacy, also play a role in the deteriorating US-Ukraine relationship, according to Dr Jessica Genauer, a senior lecturer in international relations at Flinders University.
Genauer said personal friction between the two leaders "goes back many years", and she believes Trump "probably doesn't like Zelenskyy very much".
"And at the intercountry level, President Trump clearly thinks ... that Ukraine essentially needs to capitulate at this stage of its war with Russia," she said.
"And he appears to feel more sympathy or alignment with (Russian) President (Vladimir) Putin and President Putin's position than he does with President Zelenskyy, which is certainly a break with the previous US administration."
She said the outburst from Trump and Vance, and their administration's approach to foreign policy, could represent a "new world order" being created.
"I'm not saying the old order didn't have a lot of problems and challenges and issues," Genauer said.
"But I think we need to be clear about the fact that we are now moving into a world where there will be a lot more uncertainty about how these type of high level visits might play out, about the type of behaviour that we might expect from political leaders, political actors, and their counterparts."
What is the US-Ukraine critical minerals deal?
At the centre of the Trump-Zelenskyy spat is the proposed critical minerals deal, which Zelenskyy had travelled to Washington to sign.
The US had proposed securing half of Ukraine's critical minerals, including graphite, uranium, titanium and lithium, which is essential for electric car batteries.
Ukraine has deposits of 22 of the 34 minerals identified as critical, as reported by Reuters. The country is estimated to hold around 5 per cent of the world's mineral resources.
Ukraine also claims to have 500,000 tons of lithium reserves and one-fifth of the world’s graphite, a crucial part of nuclear power stations, according to European Commission research.
It is believed the mineral deal would have given Washington access to Kyiv's untapped resources in exchange for investment and security.
But after the spat, a senior White House official told Reuters Trump was "not interested" in revisiting or reviving the deal.
Will US-Ukraine relations impact war with Russia?
Following the outburst, several European leaders affirmed their support for Ukraine, which Sussex says indicates they will likely continue to back the country militarily and financially in the war against Russia.
"It was interesting to see some comments from the Polish foreign minister Radosław Sikorski who said that with European support the Ukrainians could fight on until the end of the year and well into next year," Sussex said.
"And that's interesting because the longer the conflict goes on, it then starts to put pressure on the Russian economy."
But while Ukraine may have the ongoing support of European allies, the US has been a key partner in the war with Russia.
Without US support, Genauer says Ukraine would be left in a "very difficult position".
"I think what's obvious is that the US is not going to be leading on any kind of support endeavor or trajectory for Ukraine in the war against Russia," she said.
"So any agreement made or political settlement that's made under a Trump presidency, I think we can confidently say, will not be in Ukraine's favour."
What will happen to the US relationship with Europe?
Sussex said it could also have "seismic effects" for US relationships with European countries and other allies around the world.
"They will now look at how Zelenskyy was treated and they will say 'America is completely unreliable as a security ally'," he said.
"There is a realisation that Europe now is basically responsible for its own security, and that has knock-on effects too in Asia, and in our own backyard.
"Japan, South Korea, Australia ... all countries that have security relationships with the United States will be thinking, 'can we rely on the Trump administration for support?'".
Germany's d whether the North Atlantic Treaty Organization would remain in its "current form" in light of the comments by Trump's administration, and that Europe must quickly establish an independent defence capability.
Positions espoused by Trump and since have raised concerns about whether he is committed to upholding , which states that if a member country is attacked, all other member countries will help defend it.
Ultimately, Sussex says it is difficult to predict the next steps of the Trump administration and its relationships with Ukraine, Russia, and other powers.
"Who knows with the Trump administration, what happens today could be completely different to what happens tomorrow," he said.
"Anyone looking for consistency and clarity from this White House is going to be really badly disappointed."
-Additional reporting by Reuters
