KYIV, Aug 17 (Reuters) - Ukraine will not be able to operate U.S.-built F-16 fighter jets this coming autumn and winter, air force spokesperson Yuriy Ihnat told Ukrainian television late on Wednesday.

"It's already obvious we won't be able to defend Ukraine with F-16 fighter jets during this autumn and winter," Ihnat told a joint telethon broadcast by Ukrainian channels.

Ukraine has repeatedly called its Western allies to supply the country with F-16s, which Ukrainian President Volodymyr Zelenskiy said would be a signal that Russia's invasion would end in defeat.

U.S. President Joe Biden endorsed training programmes for Ukrainian pilots on F-16s in May but no timing for the supply of war planes has been given so far.

"We had big hopes for this plane, that it will become part of air defence, able to protect us from Russia's missiles and drones terrorism," Ihnat said.

The West says it wants to help Ukraine defeat Russia but has repeatedly insisted it does not want to trigger a direct confrontation between the U.S.-backed NATO military alliance and Moscow.