"We need very much unity between the United States and EU and countries of Europe," Zelenskiy said on Thursday before addressing European Union leaders at the start of an EU summit dominated by the Ukraine war that Trump has vowed to end.
"We need this unity to achieve peace. I think only together the United States and Europe can really stop Putin and save Ukraine," Zelenskiy continued, referring to Russian President Vladimir Putin.
EU leaders will reaffirm their "unwavering" support of Ukraine "for as long as it takes". (AP PHOTO)
EU diplomats have said the leaders aim to send a clear signal to Trump about their continued support for Ukraine and will stress that any peace settlement must involve Ukraine and respect its territorial integrity.
Antonio Costa, chairing his first EU summit as the new European Council president, said the EU would work for a just and lasting peace.
"This war is not only about Ukraine, is not only about Europe, (it) is about the international law. The international law must prevail and the invasion must be defeated," he told reporters beside Zelenskiy.
EU leaders are due to reaffirm their "unwavering commitment" to supporting Ukraine "for as long as it takes", according to draft summit conclusions.
Trump has repeatedly called for a swift end to the nearly three-year-old war.
On Monday he said Zelenskiy should be ready to reach a peace deal with Russian President Vladimir Putin, though he did not say whether this meant Kyiv ceding territory to Moscow as part of a negotiated settlement.
Russian forces occupy nearly a fifth of Ukrainian territory and are making steady advances in the east of the country.
EU draft conclusions for the summit say that "Russia must not prevail", adding that no initiative must be taken on Ukraine without Kyiv's involvement.
Donald Trump said Volodymyr Zelenskiy should be ready to reach a peace deal with Vladimir Putin. (AP PHOTO)
Zelenskiy's attendance at the EU summit follows talks with NATO Secretary-General Mark Rutte and other European leaders on Wednesday, aiming to get immediate help to bolster Kyiv's war effort and discuss longer-term security guarantees.
While European leaders insist they are focusing on Ukraine's immediate needs, some officials have begun discussing how to assure the country's security after the war comes to a halt.
The EU leaders will also discuss wider EU-US relations over lunch amid concerns of a possible trans-Atlantic trade war.
Trump has said the EU will "pay a big price" with tariffs for not buying enough US exports.
He has already pledged hefty tariffs on three of the United States' largest trading partners - Canada, Mexico and China.
The EU knows it will not be spared, and will seek to point out that it is the United States' second-biggest trading partner and a close ally with shared values.
However, mindful that Trump is preoccupied by the US goods trade deficit, EU officials have mooted potentially offering to buy more US LNG or arms.
The lunchtime "EU in the world" debate is also likely to include China and whether the bloc will be forced to take sides in a US-China trade conflict as well as Britain, which has said it wants to reset ties with the European Union and is seen by the bloc as a crucial security ally.
