An armed MQ-9 Reaper unmanned aerial vehicle, or drone the manufacturer, General Atomic Aeronautical Systems, wants to supply them to Ukraine and is seeking US government permission
An anti-aircraft rocket rises across the sky near Ukraines Soledar town

Two Ukrainian pilots are in Arizona to fly flight simulators and be evaluated by the U.S. military, two U.S. officials said on Saturday, as Washington remains mute on whether it will send fighter jets or sophisticated remotely piloted drones to Kyiv.

The U.S. and allies have been flooding Ukraine with weapons from Javelin missiles to HIMARS rocket launchers, but sophisticated jets and the largest armed drones have not been pledged to Ukraine by Western allies.

The Arizona "familiarization event" is a first and will facilitate dialogue between Ukrainian and U.S. personnel and provide an opportunity to observe how the U.S. Air Force operates, a U.S. defense official said, speaking on condition of anonymity.

"This event allows us to better help Ukrainian pilots become more effective pilots and better advise them on how to develop their own capabilities," the defense official said.

"The program involves watching how Ukrainian pilots conduct their mission planning and execution in flight simulators in order to determine how we can better advise the Ukrainian Air Force on how to use capabilities they have," an administration official said on condition of anonymity.

Other allies have also conducted similar events in the past, the defense official said. The defense official did not say how long the Ukrainians had been in the Southwestern state.

The officials said there were no updates regarding F-16 fighter jet pledges to Ukraine.

"It's about training them on their own planes," the administration official said, "not about F-16s."

The U.S. has not begun any F-16 training of Ukrainians, Colin Kahl, under secretary of defense for policy, told members of the House of Representatives on Tuesday.

Training on military equipment, both for its use and maintenance, has been a leading indicator of a potential transfer.

Kahl made the remarks during a hearing focused on oversight of the nearly $32 billion in military aid President Joe Biden's administration has provided to Ukraine since Russia's invasion a year ago, including drones, long-range artillery systems and air defense capabilities.

The Pentagon's assessment for even the most expeditious delivery of F-16s and concurrent training is 18 months, "so you don't actually save yourself time by starting the training early," Kahl told the panel.

Complicating matters is that there is no clear fleet that Ukraine could get, according to Kahl. "They could end up getting British Tornados or (Swedish) Gripens or (French) Mirage aircraft, so you wouldn't want to train them on F-16s," he said.

NBC News reported on the pilot's presence in Arizona earlier Saturday.