Several countries, including Poland, have already started training Ukrainian pilots to use U.S.-built F-16 fighter jets, the European Union's chief diplomat Josep Borrell said on May 23.
"It will take time, but sooner, the better," Borrell told reporters ahead of a meeting of EU defense ministers. He didn't mention what other countries have begun the training.
A source in the Polish government confirmed information about the F-16 training to the Ukrainian news outlet Ukrinform. An official announcement will be made soon, said the source.
The U.K. and the Netherlands agreed on May 17 to build an international coalition to provide F-16s to Ukraine. On May 20, the U.S. also declared that it would join the initiative, as did Portugal and Denmark.
According to Ukraine's Foreign Minister Dmytro Kuleba, some countries have expressed their willingness to train Ukrainian soldiers to operate Western fighter jets, and others are ready to provide the aircraft.
However, Ukraine has shown the most interest in the U.S.-built F-16, which has been in service since the 1970s and operated by over 20 nations.
Critics argue that allies' reluctance to supply Western fighter jets and long-range missiles to Ukraine may prolong Russia's war of aggression and result in thousands of deaths.