CDU leader Friedrich Merz has called on the federal government to quickly implement the so-called tank ring exchange with Poland to help Ukraine.
It would not be good if Poland's disappointment over delays was confirmed, Merz said on Wednesday on the first day of his visit to Warsaw.
"We are all facing this great challenge caused by the war in Ukraine."
Germany must meet the commitments it has made.
Warsaw is disappointed with the slow ring exchange: it has given over 200 tanks to Ukraine as military aid, but is unhappy with the German compensation offer.
"This compensation must be paid, as the Polish government expects," said Merz.
After a conversation with the chairman of the national conservative ruling party PiS, Jaroslaw Kaczynski, Merz underlined the issues on which there was disagreement.
The EU's rule of law procedure against Poland, which was criticized in Warsaw, stems from the treaties "that we all signed".
It is about restricting the independence of the judiciary.
The Polish side strongly emphasized the question of reparations for the damage caused by Germany in World War II, said PiS spokesman Radoslaw Fogiel.
The question must finally be resolved.
In Poland, a report is being prepared with demands in the billions, which Kaczynski has previously stated is to be published on September 1st.
"I told him that we see no legal basis for such reparation claims," said Merz.
Instead, there are very good reasons for joint projects with the Polish government, for example in security policy.
Many could also be realized together with France in the so-called Weimar Triangle.
A meeting with the Polish Prime Minister Mateusz Morawiecki is planned for Thursday.