Ukrainian officials are requesting the US to accept more Ukrainian pilots for F-16 pilot training.

Unnamed Ukrainian officials told Politico that the current pipeline isn’t producing enough aviators to fly the jets that will be soon donated to Kyiv.

According to the publication, Ukraine says it has 30 pilots eligible to start training in the U.S. immediately.

Yet the Biden administration has told Kyiv it lacks the school seats in its program to accept more than 12 pilot trainees at a time.

Two other facilities in Denmark and Romania have a similar issue with available training spots.

According to the publication, Ukraine has officially requested the U.S. train the additional pilots at Morris Air National Guard base in Tucson, Arizona, in a series of meetings and calls over the last several weeks.

U.S. lawmakers also put pressure on the administration to approve additional training.

But the U.S. has told the Ukrainian military that in addition to limited space, other countries are in line for F-16 training at the base and that it cannot break its commitments to those nations.

According to the Air Force spokesperson, the National Guard is planning to train a total of 12 Ukrainian pilots at the Tucson location by the end of September.

Aside from Arizona, the training facility in Denmark also has limited space. A third program, located in Romania and run by contractors, is not yet up and running.

“A total of 20 Ukrainian F-16 pilots are expected to complete the program by the end of this year – half of the 40 needed to operate a full squadron of 20 jets,” the journalists write.

In May, the Czech Republic handed over an F-16 fighter jet trainer to the Ukrainian Air Force. The simulator allows pilots to memorize the location of the fighter jet’s controls, practice flight elements, and use weapons.