(The Hill) – The Polish government on Tuesday said it is ready to “immediately” deploy its entire fleet of MiG-29 fighter jets to a U.S. air base in Germany, giving Washington the chance to then send the planes to Ukrainian forces.

“After consultations between the President and the Government,” Poland is “ready to deploy – immediately and free of charge – all their MIG-29 jets to the Ramstein Air Base and place them at the disposal of the Government of the United States of America,” Poland said in a statement.

“The Polish Government also requests other NATO Allies – owners of MIG-29 jets – to act in the same vein.”

The proposed transfer of the Soviet-era fighter jets is notable as Ukraine for days has pleaded with Western officials to help it counter the brutal Russian assault on the country with either a “no-fly zone” over its airspace or the transfer of aircraft that Ukrainian pilots could fly.

However, the Pentagon later on Tuesday appeared to reject Warsaw’s plan.

“The prospect of fighter jets ‘at the disposal of the Government of the United States of America’ departing from a U.S./NATO base in Germany to fly into airspace that is contested with Russia over Ukraine raises serious concerns for the entire NATO alliance,” Pentagon press secretary John Kirby said in a statement. 

“It is simply not clear to us that there is a substantive rationale for it. We will continue to consult with Poland and our other NATO allies about this issue and the difficult logistical challenges it presents, but we do not believe Poland’s proposal is a tenable one,” he added. 

Ukrainian President Volodymyr Zelensky on Saturday implored U.S. lawmakers to send the Russian-made MiGs, which Ukrainian pilots are already trained to fly.

The United States and other nations have been reluctant to draw the ire of Russia with such a major arms transfer. Moscow has warned that any nation that gives Ukraine aircraft to use to fight Kremlin forces could be seen as participating in the conflict. 

On Sunday, Secretary of State Antony Blinken said the plan had gotten “the green light” from the U.S. and that the Biden administration would then work to backfill the Polish military, reportedly with F-16 fighter jets. 

Poland touched on that plan in its Tuesday statement, asking the U.S. to “provide us with used aircraft with corresponding operational capabilities,” in place of the MiGs, of which it has 27, according to Janes.  

The White House has tempered expectations, however, with press secretary Jen Psaki on Monday pointing to the complicated logistics of backfilling planes for its allies. 

Procuring new planes and transferring serious weapons systems “often take years to do from the United States,” she told reporters.

Additionally, Poland’s offer to transfer the jets wasn’t “preconsulted” with the United States prior to the Tuesday announcement, according to Undersecretary of State for Political Affairs Victoria Nuland. 

“I saw that announcement by the government of Poland as I was literally driving here today,” Nuland told lawmakers at a Senate Foreign Relations Committee hearing.

“So to my knowledge, it wasn’t pre-consulted with us that they plan to give these planes to us,” she said, adding that after the hearing ended she would return to her desk and see “how we will respond to this proposal of theirs to give the planes to us.”