Poland has agreed to send German-made Leopard 2 tanks to Ukraine as part of a larger international coalition.
Polish President Andrzej Duda made the announcement after a meeting in Lviv with Ukrainian President Volodymyr Zelensky, who said his country needs tanks to win the war.
The Leopard 2 tank is widely regarded as the best of its kind in the world, combining both speed and accuracy, and capable of hitting targets 5km away while on the move.
Speaking during his visit to the western Ukrainian city, Mr Duda said: "A company of Leopard tanks will be handed over as part of coalition-building. We want it to be an international coalition."
Mr Duda said a company, which typically consists of 14 tanks, would hopefully soon travel from Poland to Ukraine, together with tanks from other countries.
The news was met with a positive response from the Ukrainian military, who tweeted their thanks and said they were "very happy to host them here", adding that the Leopard tanks "won't go hungry."
Mr Zelensky has been pressing Nato for months to provide his forces with US Abrams and Leopard II battle tanks.
His request was echoed by Western officials, who warned that Ukraine will not be able to take back significant territory from Russia without an increase in fighting power, including tanks and other heavy armour.
Officials said the two sides were currently too closely matched for the Ukrainians to be able to mount a successful offensive.
There is growing speculation that British Challenger 2 battle tanks could be sent to Ukraine, but Prime Minister Rishi Sunak's spokesman said no final decision has been made.