(Bloomberg) -- Poland sent its first four Leopard 2A4 battle tanks to Ukraine, a symbolic gesture to mark one year since Russia’s invasion as western allies rush to arm the embattled nation’s forces amid intensified Kremlin-ordered attacks. 

Prime Minister Mateusz Morawiecki announced during a visit to Kyiv on Friday that the delivery of the remaining batch of its 14 German-made combat vehicles will follow soon. Poland will also send 60 modernized Soviet-era PT-91 tanks in the coming days, he added.

The arrival of the older-model Leopards follows an intense lobbying campaign from Warsaw. It culminated last month in Germany’s agreement to deliver state-of-the-art Leopard 2A6 tanks to Kyiv, unlocking similar pledges from the US and other European allies to send other modern tanks from their inventories. 

Spanish Prime Minister Pedro Sanchez said in Kyiv Thursday that his government is considering increasing the number of Leopard tanks it will ship to Ukraine to 10 from six. Poland has been assembling a coalition of countries to send the older A4 version of the Leopard 2, while Germany is working with allies to supply the modern A6 version. 

German Defense Minister Boris Pistorius indicated earlier this month that western allies are struggling to put together two full battalions of the tanks to send to Ukraine as promised. 

The government in Warsaw is also ready to train Ukrainian pilots to fly F-16 fighter jets, but any delivery of such aircrafts will have to be agreed among NATO allies, Morawiecki said. 

(Updates with number of tanks in the first paragraph.)

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