US and European sources told Politico that several countries that vowed this week to train Ukrainian pilots on the use of American F-16 fighter jets are currently waiting for the United States to formally authorize the program.

During last week's NATO summit in Vilnius, Lithuania, a coalition of 11 states led by Denmark and the Netherlands formally committed to training Ukrainians to fly F-16s and other fighter aircraft.

According to European officials, the training program is expected to begin in August in Denmark, and a training facility is set to be established in Romania.

Nonetheless, Politico indicated that the training cannot begin until the US Department of State formally approves the request to transfer instruction manuals, flight simulators, and other documents about the jets.

While US President Joe Biden has vowed to approve the program, the official request "is still being reviewed," the news website quoted Lt. Col. Garron Garn, a Pentagon spokesperson, as saying.

It is noteworthy that last month, Pentagon Spokesperson Patrick Ryder confirmed that Denmark officially requested permission to conduct F-16 training.

The news website pointed out that it is not uncommon for the United States' interagency procedure to authorize the transfer of sensitive military technology, especially fighter jets, to take time.

This comes as senior Ukrainian officials indicated that Kiev is in urgent need of F-16s.

Speaking before the NATO summit in early July, Ukrainian President Volodymyr Zelensky chastised the West for delaying the training of Ukrainian pilots.

"I have the same questions as you do for our esteemed partners," he said in response to a question about the fighter jets' delivery dates.

"We have agreed, we have pressed, and we have a coalition of countries that are ready to start training for Ukrainian pilots. [But] there is no schedule for training missions, and they’re delaying it. I don’t know why they’re doing this," Zelensky added.

The Pentagon’s Joint Staff Director for Operations Lt. Gen. Douglas Sims II suggested on Thursday that the conditions on the battlefield in Ukraine were "not ideal" for using F-16 fighter jets at present given that Russia continues to possess air defense capabilities.

"The Russians still possess some air defense capability. They have air capability. And the number of F-16s that would be provided may not be perfect for what’s going on right now," Sims explained.

"As the future changes, that certainly will dictate how that is employed."

On his part, Russian Foreign Minister Sergey Lavrov said on Thursday that Russia will consider the presence of F-16 fighter jets in Ukraine sent from the West as a "nuclear" threat due to their capacity to carry atomic weapons.

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