German Chancellor Olaf Scholz, French President Emmanuel Macron and Italian Prime Minister Mario Draghi arrived in Kiev on Thursday morning for their first visit since the Russian invasion.
They will speak with President Volodymyr Zelensky about further support for the country and Ukraine's desire to be admitted to the European Union.
The leaders of the three largest economies in the European Union - all also members of the G7 - constitute the most important European delegation to Ukraine since the war began in late February.
With the air space over Ukraine blocked off to civilian flights due to the war, the leaders made the trip via a nine-wagon train from Poland. They set off for Kiev from the Polish border town of Przemyśl shortly before midnight.
The overnight train trip had been planned for days. But it was not officially confirmed until shortly before arrival in the Ukrainian capital for security reasons.
Romanian President Klaus Iohannis is scheduled to join the group in Kiev, but took a different itinerary.
For Scholz in particular, the visit is a watershed moment after weeks of debate over whether he should have visited before now in order to show Berlin's support for Ukraine. Zelensky has consistently pressured German leaders to do more to help fight the Russians, including sending heavy weaponry such as tanks.
The issue of arms deliveries and other support, as well as Ukraine's application to join the European Union will be high on the agenda of the talks with Ukraine's leadership.
On Wednesday, Germany announced it will provide Ukraine with three MARS II multiple rocket launch systems. Ukraine will also be provided missiles for the launchers, train Ukrainian soldiers in operating the systems and provide replacement parts.