(Brussels) Ukrainian President Volodymyr Zelensky on Thursday thanked the Europeans for their military aid, but warned that prejudices over the supply of long-range missiles and fighter jets risked prolonging the war.

Returning from the Kherson region, near the southern front, the president called, via videoconference from a train, the European leaders meeting at the summit in Brussels.

The connection was interrupted once, but the Ukrainian president was able to deliver his message, said a European official.

He warned against refusing to supply his forces with long-range missiles and modern fighter jets.

The Ukrainian president also called for the adoption of new sanctions against Russia, progress on his country’s accession to the EU and progress on his peace plan.

Delays on these various points could still “prolong the war”, he warned, quoted by the European official.

The West considers that Ukraine has the right to defend itself against Russian aggression and that they contribute to this defense with their arms supplies.

But many are reluctant to deliver weapons that would escalate the conflict by allowing Ukraine to hit Russia.

Some European countries, however, have announced that they are ready to supply Ukraine with Soviet-made fighter jets. Four MIG-29s were delivered to Ukraine on Thursday, the Slovak Defense Ministry said. Poland has also promised to provide 4 MIG-29s.

But Kyiv is calling for modern fighter bombers, including American F-16s.

The Europeans approved Monday the allocation of 2 billion euros to finance joint purchases of artillery ammunition which Ukraine desperately needs to counter the offensive of Russian troops.