The new Polish Prime Minister Donald Tusk and Ukrainian President Volodymyr Zelensky spoke in Kiev on Monday about trade problems along their borders and agreed they would work together to solve the issues so no international mediators are needed.

Tusk, at a press conference, said the two sides developed a mutual understanding of the situation and reaffirmed that the best option is “to solve problems together.”

Polish farmers fear the import of cheap grain from Ukraine. Tusk’s government, in office since December, has maintained import restrictions.

Although Poland is politically and militarily one of the closest allies of Ukraine, which is under attack from Russia, Polish lorry drivers recently blocked border crossings for weeks out of anger at what they see as unfair Ukrainian competition.

Ministers from both sides took part in the talks. Tusk did not provide any details on possible solutions. Zelensky explained that Ukraine was not only defending its own independence, but that of the whole of Europe, including Poland.

“Solidarity with Ukraine should not be undermined by any obstacles,” Zelensky wrote on Facebook.