Despite previous reports to the contrary, the United States is indeed considering sending fighter jets to Ukraine and training their pilots how to fly them, Air Force Secretary Frank Kendall says.

Kendall, speaking Wednesday at the Aspen Security Forum, noted that Ukraine is having to deal with its “right now problem” of ground-based fighting in the Donbas region, but he added that aircraft may also be needed, the Daily Mail reported.

“We’ll be open to discussions with them about what their requirements are and how we might be able to satisfy them,” Kendall said, adding that it is “largely up to Ukraine” to decide what type of aircraft it wants.

Ukrainian President Volodomyr Zelenskyy has said he needs advanced fighter jets such as F-15s and F-16s.

Just last week, the House of Representatives passed the National Defense Authorization Act. The House’s version of the legislation would provide $100 million to train Ukrainian pilots to fly U.S. aircraft.

In the past, Kendall has downplayed any idea that the United States would send A-10s to Ukraine, but he did not completely shut down such a plan at the Aspen conference, the Daily Mail reported.

“There are a number of international opportunities that are possible there,” he said. “Older U.S. systems are a possibility.”

Air Force Chief of Staff Gen. Charles Brown Jr., who also spoke at the conference, told Reuters in an interview before the forum that the U.S. and its allies are looking into ideas for a long-term program to train Ukrainian pilots and to modernize its air force.

In his speech on Wednesday, Brown said that Ukraine’s success in defeating Russia’s invasion is a sign of the benefits of U.S. and Ukrainian military cooperation.

With the West’s provision of anti-aircraft weapons, Ukraine has been able to prevent Russia from using its far more advanced air force to establish dominance in the skies since Moscow invaded Ukraine on Feb. 24.

“You want to build a long-term plan on how do you build their air force and the air force that they’re going to need for the future,” said Brown, a pilot himself, without confirming any decisions on the way forward.

Brown did not comment on the legislation. He also declined to speculate on timelines or what kinds of Western aircraft might be best suited to Ukraine.

But he stressed that future training of Ukrainian pilots was a complex question, one that would need to take in account the state of the war and Kyiv’s ability to remove pilots from the fight to undergo lengthy instruction.

“How can you make that transition from where we are today to where we are going to want to be in the future? To allow folks to leave to go train,” he said.

Asked how long it might take for a Ukrainian pilot to transition to U.S. fighter aircraft, Brown noted that a U.S. pilot could train on a new type of aircraft in a matter of perhaps two to four months. Transitioning from a Soviet system would be “a little harder,” he said.

Brown said Ukraine could look to NATO allies with experience transitioning from Soviet-era aircraft to Western systems.

“I feel pretty confident there are some of our NATO partners who have done that, can actually have lessons that they learned that can be helpful to the Ukrainians to help them figure out how to best make that transition,” Brown said.